feat: add display UI with splash screen, dashboard, and RSSI sparkline

Implement full SSD1306 OLED display support:
- Splash screen on boot (1.5s) with project name, version, board
- Dashboard showing radio state, config, counters, RSSI/SNR
- RSSI history sparkline (64-sample ring buffer, 2px-wide bars)
- DisplayOn/DisplayOff host commands routed via dedicated channel
- Pure render functions against generic DrawTarget (no hardware coupling)
- Display on/off control bypasses radio task entirely

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vendor/crunchy/.cargo-checksum.json

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vendor/crunchy/.cargo_vcs_info.json

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+{
+  "git": {
+    "sha1": "ba7b86cea6ba89ccfc72ccb24cc4a4ac6d9c6272"
+  },
+  "path_in_vcs": ""
+}

vendor/crunchy/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "crunchy"
+version = "0.2.4"

vendor/crunchy/Cargo.toml

@@ -0,0 +1,43 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+edition = "2021"
+name = "crunchy"
+version = "0.2.4"
+authors = ["Eira Fransham <jackefransham@gmail.com>"]
+build = "build.rs"
+autolib = false
+autobins = false
+autoexamples = false
+autotests = false
+autobenches = false
+description = "Crunchy unroller: deterministically unroll constant loops"
+homepage = "https://github.com/eira-fransham/crunchy"
+readme = "README.md"
+license = "MIT"
+repository = "https://github.com/eira-fransham/crunchy"
+
+[features]
+default = ["limit_128"]
+limit_1024 = []
+limit_128 = []
+limit_2048 = []
+limit_256 = []
+limit_512 = []
+limit_64 = []
+std = []
+
+[lib]
+name = "crunchy"
+path = "src/lib.rs"
+
+[dependencies]

vendor/crunchy/LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright 2017-2023 Eira Fransham.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

vendor/crunchy/README.md

@@ -0,0 +1,39 @@
+# Crunchy
+
+The crunchy unroller - deterministically unroll constant loops. For number
+"crunching".
+
+The Rust optimizer will unroll constant loops that don't use the loop variable,
+like this:
+
+```rust
+for _ in 0..100 {
+  println!("Hello!");
+}
+```
+
+However, using the loop variable will cause it to never unroll the loop. This is
+unfortunate because it means that you can't constant-fold the loop variable, and
+if you end up stomping on the registers it will have to do a load for each
+iteration. This crate ensures that your code is unrolled and const-folded. It
+only works on literals, unfortunately, but there's a work-around:
+
+```rust
+debug_assert_eq!(MY_CONSTANT, 100);
+unroll! {
+  for i in 0..100 {
+    println!("Iteration {}", i);
+  }
+}
+```
+
+This means that your tests will catch if you redefine the constant.
+
+To default maximum number of loops to unroll is `128`, but that can be easily decreased or increased using the cargo features:
+
+* `limit_64`
+* `limit_128`
+* `limit_256`
+* `limit_512`
+* `limit_1024`
+* `limit_2048`

vendor/crunchy/build.rs

@@ -0,0 +1,255 @@
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::Path;
+
+const LOWER_LIMIT: usize = 16;
+
+fn main() {
+    let limit = if cfg!(feature="limit_2048") {
+        2048
+    } else if cfg!(feature="limit_1024") {
+        1024
+    } else if cfg!(feature="limit_512") {
+        512
+    } else if cfg!(feature="limit_256") {
+        256
+    } else if cfg!(feature="limit_128") {
+        128
+    } else {
+        64
+    };
+
+    let out_dir = env::var("OUT_DIR").unwrap();
+    let dest_path = Path::new(&out_dir).join("lib.rs");
+    let mut f = File::create(&dest_path).unwrap();
+
+    let mut output = String::new();
+
+    output.push_str(r#"
+/// Unroll the given for loop
+///
+/// Example:
+///
+/// ```ignore
+/// unroll! {
+///   for i in 0..5 {
+///     println!("Iteration {}", i);
+///   }
+/// }
+/// ```
+///
+/// will expand into:
+///
+/// ```ignore
+/// { println!("Iteration {}", 0); }
+/// { println!("Iteration {}", 1); }
+/// { println!("Iteration {}", 2); }
+/// { println!("Iteration {}", 3); }
+/// { println!("Iteration {}", 4); }
+/// ```
+#[macro_export]
+macro_rules! unroll {
+    (for $v:ident in 0..0 $c:block) => {};
+
+    (for $v:ident < $max:tt in ($start:tt..$end:tt).step_by($val:expr) {$($c:tt)*}) => {
+        {
+            let step = $val;
+            let start = $start;
+            let end = start + ($end - start) / step;
+            unroll! {
+                for val < $max in start..end {
+                    let $v: usize = ((val - start) * step) + start;
+
+                    $($c)*
+                }
+            }
+        }
+    };
+
+    (for $v:ident in ($start:tt..$end:tt).step_by($val:expr) {$($c:tt)*}) => {
+        unroll! {
+            for $v < $end in ($start..$end).step_by($val) {$($c)*}
+        }
+    };
+
+    (for $v:ident in ($start:tt..$end:tt) {$($c:tt)*}) => {
+        unroll!{
+            for $v in $start..$end {$($c)*}
+        }
+    };
+
+    (for $v:ident in $start:tt..$end:tt {$($c:tt)*}) => {
+        #[allow(non_upper_case_globals)]
+        #[allow(unused_comparisons)]
+        {
+            unroll!(@$v, 0, $end, {
+                    if $v >= $start {$($c)*}
+                }
+            );
+        }
+    };
+
+    (for $v:ident < $max:tt in $start:tt..$end:tt $c:block) => {
+        #[allow(non_upper_case_globals)]
+        {
+            let range = $start..$end;
+            assert!(
+                $max >= range.end,
+                "`{}` out of range `{:?}`",
+                stringify!($max),
+                range,
+            );
+            unroll!(
+                @$v,
+                0,
+                $max,
+                {
+                    if $v >= range.start && $v < range.end {
+                        $c
+                    }
+                }
+            );
+        }
+    };
+
+    (for $v:ident in 0..$end:tt {$($statement:tt)*}) => {
+        #[allow(non_upper_case_globals)]
+        { unroll!(@$v, 0, $end, {$($statement)*}); }
+    };
+
+"#);
+
+    for i in 0..limit + 1 {
+        output.push_str(format!("    (@$v:ident, $a:expr, {}, $c:block) => {{\n", i).as_str());
+
+        if i <= LOWER_LIMIT {
+            output.push_str(format!("        {{ const $v: usize = $a; $c }}\n").as_str());
+
+            for a in 1..i {
+                output.push_str(format!("        {{ const $v: usize = $a + {}; $c }}\n", a).as_str());
+            }
+        } else {
+            let half = i / 2;
+
+            if i % 2 == 0 {
+                output.push_str(format!("        unroll!(@$v, $a, {0}, $c);\n", half).as_str());
+                output.push_str(format!("        unroll!(@$v, $a + {0}, {0}, $c);\n", half).as_str());
+            } else {
+                if half > 1 {
+                    output.push_str(format!("        unroll!(@$v, $a, {}, $c);\n", i - 1).as_str())
+                }
+
+                output.push_str(format!("        {{ const $v: usize = $a + {}; $c }}\n", i - 1).as_str());
+            }
+        }
+
+        output.push_str("    };\n\n");
+    }
+
+    output.push_str("}\n\n");
+
+    output.push_str(format!(r#"
+#[cfg(all(test, feature = "std"))]
+mod tests {{
+    #[test]
+    fn invalid_range() {{
+        let mut a: Vec<usize> = vec![];
+        unroll! {{
+                for i in (5..4) {{
+                    a.push(i);
+                }}
+            }}
+        assert_eq!(a, vec![]);
+    }}
+
+    #[test]
+    fn start_at_one_with_step() {{
+        let mut a: Vec<usize> = vec![];
+        unroll! {{
+                for i in (2..4).step_by(1) {{
+                    a.push(i);
+                }}
+            }}
+        assert_eq!(a, vec![2, 3]);
+    }}
+
+    #[test]
+    fn start_at_one() {{
+        let mut a: Vec<usize> = vec![];
+        unroll! {{
+                for i in 1..4 {{
+                    a.push(i);
+                }}
+            }}
+        assert_eq!(a, vec![1, 2, 3]);
+    }}
+
+    #[test]
+    fn test_all() {{
+        {{
+            let a: Vec<usize> = vec![];
+            unroll! {{
+                for i in 0..0 {{
+                    a.push(i);
+                }}
+            }}
+            assert_eq!(a, (0..0).collect::<Vec<usize>>());
+        }}
+        {{
+            let mut a: Vec<usize> = vec![];
+            unroll! {{
+                for i in 0..1 {{
+                    a.push(i);
+                }}
+            }}
+            assert_eq!(a, (0..1).collect::<Vec<usize>>());
+        }}
+        {{
+            let mut a: Vec<usize> = vec![];
+            unroll! {{
+                for i in 0..{0} {{
+                    a.push(i);
+                }}
+            }}
+            assert_eq!(a, (0..{0}).collect::<Vec<usize>>());
+        }}
+        {{
+            let mut a: Vec<usize> = vec![];
+            let start = {0} / 4;
+            let end = start * 3;
+            unroll! {{
+                for i < {0} in start..end {{
+                    a.push(i);
+                }}
+            }}
+            assert_eq!(a, (start..end).collect::<Vec<usize>>());
+        }}
+        {{
+            let mut a: Vec<usize> = vec![];
+            unroll! {{
+                for i in (0..{0}).step_by(2) {{
+                    a.push(i);
+                }}
+            }}
+            assert_eq!(a, (0..{0} / 2).map(|x| x * 2).collect::<Vec<usize>>());
+        }}
+        {{
+            let mut a: Vec<usize> = vec![];
+            let start = {0} / 4;
+            let end = start * 3;
+            unroll! {{
+                for i < {0} in (start..end).step_by(2) {{
+                    a.push(i);
+                }}
+            }}
+            assert_eq!(a, (start..end).filter(|x| x % 2 == 0).collect::<Vec<usize>>());
+        }}
+    }}
+}}
+"#, limit).as_str());
+
+    f.write_all(output.as_bytes()).unwrap();
+
+    println!("cargo:rustc-env=CRUNCHY_LIB_SUFFIX={}lib.rs", std::path::MAIN_SEPARATOR);
+}

vendor/crunchy/src/lib.rs

@@ -0,0 +1,37 @@
+//! The crunchy unroller - deterministically unroll constant loops. For number "crunching".
+//!
+//! The Rust optimizer will unroll constant loops that don't use the loop variable, like this:
+//!
+//! ```ignore
+//! for _ in 0..100 {
+//!     println!("Hello!");
+//! }
+//! ```
+//!
+//! However, using the loop variable will cause it to never unroll the loop. This is unfortunate because it means that you can't
+//! constant-fold the loop variable, and if you end up stomping on the registers it will have to do a load for each iteration.
+//! This crate ensures that your code is unrolled and const-folded. It only works on literals,
+//! unfortunately, but there's a work-around:
+//!
+//! ```ignore
+//! debug_assert_eq!(MY_CONSTANT, 100);
+//! unroll! {
+//!     for i in 0..100 {
+//!         println!("Iteration {}", i);
+//!     }
+//! }
+//! ```
+//! This means that your tests will catch if you redefine the constant.
+//!
+//! To default maximum number of loops to unroll is `64`, but that can be easily increased using the cargo features:
+//!
+//! * `limit_128`
+//! * `limit_256`
+//! * `limit_512`
+//! * `limit_1024`
+//! * `limit_2048`
+
+#![cfg_attr(not(feature = "std"), no_std)]
+
+include!(concat!(env!("OUT_DIR"), env!("CRUNCHY_LIB_SUFFIX")));
+