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/embassy-usb-synopsys-otg/.cargo-checksum.json

@@ -0,0 +1 @@
+{"files":{".cargo_vcs_info.json":"2be68853d431f212f871f14f3c1c2c75896ed853ffcc4357c3a1dddcbfcf5bc7","Cargo.toml":"ad03ae155c25a3f4cd775e4d9530e8a272e0c0e64d0ff8652ece8c04fcb4ff5c","Cargo.toml.orig":"ff79965b0fe33eda6f921dd6e5d638e5d2423ddb7698906c9086140951a0bdb3","README.md":"eaf7859730bf1326ae0201b628b42229a8f8cd25d27f9003e1bfd0eae8a6a4a2","src/fmt.rs":"8f40e9fed6e1217e0a78db94986806346c3bd33f85be4a5f753b4c5fa77bbce0","src/lib.rs":"d9ea44a9744873bb0c3767b89bec39faccefdcca30b9ff1003d00c57e5df02fa","src/otg_v1.rs":"464869a891012e66bea918f84d86729fb96c0ae0ea62a16e36511237b6653fd2"},"package":"d46be92e72bcf39e623ff74d739a8ab29b02f4909a9b05986ca81c2157ac254a"}

vendor/embassy-usb-synopsys-otg/.cargo_vcs_info.json

@@ -0,0 +1,6 @@
+{
+  "git": {
+    "sha1": "ecc910b76dbfa2064f42e6917a7b5654a89b81ed"
+  },
+  "path_in_vcs": "embassy-usb-synopsys-otg"
+}

vendor/embassy-usb-synopsys-otg/Cargo.toml

@@ -0,0 +1,56 @@
+# 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 = "embassy-usb-synopsys-otg"
+version = "0.1.0"
+description = "`embassy-usb-driver` implementation for Synopsys OTG USB controllers"
+documentation = "https://docs.embassy.dev/embassy-usb-synopsys-otg"
+readme = "README.md"
+keywords = [
+    "embedded",
+    "async",
+    "usb",
+    "hal",
+    "embedded-hal",
+]
+categories = [
+    "embedded",
+    "hardware-support",
+    "no-std",
+    "asynchronous",
+]
+license = "MIT OR Apache-2.0"
+repository = "https://github.com/embassy-rs/embassy"
+
+[package.metadata.embassy_docs]
+features = ["defmt"]
+src_base = "https://github.com/embassy-rs/embassy/blob/embassy-usb-synopsys-otg-v$VERSION/embassy-usb-synopsys-otg/src/"
+src_base_git = "https://github.com/embassy-rs/embassy/blob/$COMMIT/embassy-usb-synopsys-otg/src/"
+target = "thumbv7em-none-eabi"
+
+[dependencies.critical-section]
+version = "1.1"
+
+[dependencies.defmt]
+version = "0.3"
+optional = true
+
+[dependencies.embassy-sync]
+version = "0.5.0"
+
+[dependencies.embassy-usb-driver]
+version = "0.1.0"
+
+[dependencies.log]
+version = "0.4.14"
+optional = true

vendor/embassy-usb-synopsys-otg/README.md

@@ -0,0 +1,16 @@
+# Embassy USB driver for the Synopsys USB OTG core
+
+This crate implements [`embassy-usb-driver`](https://crates.io/crates/embassy-usb-driver) for Synopsys USB OTG devices. 
+
+It contains the "core" of the driver that is common across all chips using
+the Synopsys OTG IP, but it doesn't contain chip-specific initialization such
+as clock setup and GPIO muxing. You most likely don't want to use this crate
+directly, but use it through a HAL that does the initialization for you.
+
+List of HALs integrating this driver:
+
+- [`embassy-stm32`](https://crates.io/crates/embassy-stm32), for STMicroelectronics STM32 chips.
+- [`esp-hal`](https://crates.io/crates/esp-hal), for Espressif ESP32 chips.
+
+If you wish to integrate this crate into your device's HAL, you will need to add the 
+device-specific initialization. See the above crates for examples on how to do it.

vendor/embassy-usb-synopsys-otg/src/fmt.rs

@@ -0,0 +1,257 @@
+#![macro_use]
+#![allow(unused)]
+
+use core::fmt::{Debug, Display, LowerHex};
+
+#[cfg(all(feature = "defmt", feature = "log"))]
+compile_error!("You may not enable both `defmt` and `log` features.");
+
+macro_rules! assert {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::assert!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::assert!($($x)*);
+        }
+    };
+}
+
+macro_rules! assert_eq {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::assert_eq!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::assert_eq!($($x)*);
+        }
+    };
+}
+
+macro_rules! assert_ne {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::assert_ne!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::assert_ne!($($x)*);
+        }
+    };
+}
+
+macro_rules! debug_assert {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::debug_assert!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug_assert!($($x)*);
+        }
+    };
+}
+
+macro_rules! debug_assert_eq {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::debug_assert_eq!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug_assert_eq!($($x)*);
+        }
+    };
+}
+
+macro_rules! debug_assert_ne {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::debug_assert_ne!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug_assert_ne!($($x)*);
+        }
+    };
+}
+
+macro_rules! todo {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::todo!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::todo!($($x)*);
+        }
+    };
+}
+
+#[cfg(not(feature = "defmt"))]
+macro_rules! unreachable {
+    ($($x:tt)*) => {
+        ::core::unreachable!($($x)*)
+    };
+}
+
+#[cfg(feature = "defmt")]
+macro_rules! unreachable {
+    ($($x:tt)*) => {
+        ::defmt::unreachable!($($x)*)
+    };
+}
+
+macro_rules! panic {
+    ($($x:tt)*) => {
+        {
+            #[cfg(not(feature = "defmt"))]
+            ::core::panic!($($x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::panic!($($x)*);
+        }
+    };
+}
+
+macro_rules! trace {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::trace!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::trace!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+macro_rules! debug {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::debug!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::debug!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+macro_rules! info {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::info!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::info!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+macro_rules! warn {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::warn!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::warn!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+macro_rules! error {
+    ($s:literal $(, $x:expr)* $(,)?) => {
+        {
+            #[cfg(feature = "log")]
+            ::log::error!($s $(, $x)*);
+            #[cfg(feature = "defmt")]
+            ::defmt::error!($s $(, $x)*);
+            #[cfg(not(any(feature = "log", feature="defmt")))]
+            let _ = ($( & $x ),*);
+        }
+    };
+}
+
+#[cfg(feature = "defmt")]
+macro_rules! unwrap {
+    ($($x:tt)*) => {
+        ::defmt::unwrap!($($x)*)
+    };
+}
+
+#[cfg(not(feature = "defmt"))]
+macro_rules! unwrap {
+    ($arg:expr) => {
+        match $crate::fmt::Try::into_result($arg) {
+            ::core::result::Result::Ok(t) => t,
+            ::core::result::Result::Err(e) => {
+                ::core::panic!("unwrap of `{}` failed: {:?}", ::core::stringify!($arg), e);
+            }
+        }
+    };
+    ($arg:expr, $($msg:expr),+ $(,)? ) => {
+        match $crate::fmt::Try::into_result($arg) {
+            ::core::result::Result::Ok(t) => t,
+            ::core::result::Result::Err(e) => {
+                ::core::panic!("unwrap of `{}` failed: {}: {:?}", ::core::stringify!($arg), ::core::format_args!($($msg,)*), e);
+            }
+        }
+    }
+}
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub struct NoneError;
+
+pub trait Try {
+    type Ok;
+    type Error;
+    fn into_result(self) -> Result<Self::Ok, Self::Error>;
+}
+
+impl<T> Try for Option<T> {
+    type Ok = T;
+    type Error = NoneError;
+
+    #[inline]
+    fn into_result(self) -> Result<T, NoneError> {
+        self.ok_or(NoneError)
+    }
+}
+
+impl<T, E> Try for Result<T, E> {
+    type Ok = T;
+    type Error = E;
+
+    #[inline]
+    fn into_result(self) -> Self {
+        self
+    }
+}
+
+pub(crate) struct Bytes<'a>(pub &'a [u8]);
+
+impl<'a> Debug for Bytes<'a> {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        write!(f, "{:#02x?}", self.0)
+    }
+}
+
+impl<'a> Display for Bytes<'a> {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        write!(f, "{:#02x?}", self.0)
+    }
+}
+
+impl<'a> LowerHex for Bytes<'a> {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        write!(f, "{:#02x?}", self.0)
+    }
+}
+
+#[cfg(feature = "defmt")]
+impl<'a> defmt::Format for Bytes<'a> {
+    fn format(&self, fmt: defmt::Formatter) {
+        defmt::write!(fmt, "{:02x}", self.0)
+    }
+}