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/pin-project-lite/Cargo.toml

@@ -0,0 +1,198 @@
+# 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 = "2018"
+rust-version = "1.37"
+name = "pin-project-lite"
+version = "0.2.17"
+build = false
+exclude = [
+    "/.*",
+    "/tools",
+    "/DEVELOPMENT.md",
+]
+autolib = false
+autobins = false
+autoexamples = false
+autotests = false
+autobenches = false
+description = """
+A lightweight version of pin-project written with declarative macros.
+"""
+readme = "README.md"
+keywords = [
+    "pin",
+    "macros",
+]
+categories = [
+    "no-std",
+    "no-std::no-alloc",
+    "rust-patterns",
+]
+license = "Apache-2.0 OR MIT"
+repository = "https://github.com/taiki-e/pin-project-lite"
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+
+[package.metadata.cargo_check_external_types]
+allowed_external_types = []
+
+[lib]
+name = "pin_project_lite"
+path = "src/lib.rs"
+doc-scrape-examples = false
+
+[[test]]
+name = "compiletest"
+path = "tests/compiletest.rs"
+
+[[test]]
+name = "drop_order"
+path = "tests/drop_order.rs"
+
+[[test]]
+name = "expandtest"
+path = "tests/expandtest.rs"
+
+[[test]]
+name = "proper_unpin"
+path = "tests/proper_unpin.rs"
+
+[[test]]
+name = "test"
+path = "tests/test.rs"
+
+[dev-dependencies.rustversion]
+version = "1"
+
+[dev-dependencies.static_assertions]
+version = "1"
+
+[lints.clippy]
+all = "warn"
+as_ptr_cast_mut = "warn"
+as_underscore = "warn"
+default_union_representation = "warn"
+inline_asm_x86_att_syntax = "warn"
+pedantic = "warn"
+trailing_empty_array = "warn"
+transmute_undefined_repr = "warn"
+undocumented_unsafe_blocks = "warn"
+unused_trait_names = "warn"
+
+[lints.clippy.bool_assert_comparison]
+level = "allow"
+priority = 1
+
+[lints.clippy.borrow_as_ptr]
+level = "allow"
+priority = 1
+
+[lints.clippy.cast_lossless]
+level = "allow"
+priority = 1
+
+[lints.clippy.collapsible_match]
+level = "allow"
+priority = 1
+
+[lints.clippy.declare_interior_mutable_const]
+level = "allow"
+priority = 1
+
+[lints.clippy.doc_markdown]
+level = "allow"
+priority = 1
+
+[lints.clippy.float_cmp]
+level = "allow"
+priority = 1
+
+[lints.clippy.incompatible_msrv]
+level = "allow"
+priority = 1
+
+[lints.clippy.manual_assert]
+level = "allow"
+priority = 1
+
+[lints.clippy.manual_range_contains]
+level = "allow"
+priority = 1
+
+[lints.clippy.missing_errors_doc]
+level = "allow"
+priority = 1
+
+[lints.clippy.module_name_repetitions]
+level = "allow"
+priority = 1
+
+[lints.clippy.naive_bytecount]
+level = "allow"
+priority = 1
+
+[lints.clippy.nonminimal_bool]
+level = "allow"
+priority = 1
+
+[lints.clippy.range_plus_one]
+level = "allow"
+priority = 1
+
+[lints.clippy.similar_names]
+level = "allow"
+priority = 1
+
+[lints.clippy.single_match]
+level = "allow"
+priority = 1
+
+[lints.clippy.single_match_else]
+level = "allow"
+priority = 1
+
+[lints.clippy.struct_excessive_bools]
+level = "allow"
+priority = 1
+
+[lints.clippy.struct_field_names]
+level = "allow"
+priority = 1
+
+[lints.clippy.too_many_arguments]
+level = "allow"
+priority = 1
+
+[lints.clippy.too_many_lines]
+level = "allow"
+priority = 1
+
+[lints.clippy.type_complexity]
+level = "allow"
+priority = 1
+
+[lints.rust]
+deprecated_safe = "warn"
+improper_ctypes = "warn"
+improper_ctypes_definitions = "warn"
+non_ascii_idents = "warn"
+rust_2018_idioms = "warn"
+single_use_lifetimes = "warn"
+unnameable_types = "warn"
+unreachable_pub = "warn"
+
+[lints.rust.unexpected_cfgs]
+level = "warn"
+priority = 0
+check-cfg = []