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/winnow/src/lib.rs

@@ -0,0 +1,189 @@
+//! > winnow, making parsing a breeze
+//!
+//! `winnow` is a parser combinator library
+//!
+//! Quick links:
+//! - [List of combinators][crate::combinator]
+//! - [Tutorial][_tutorial::chapter_0]
+//! - [Special Topics][_topic]
+//! - [Discussions](https://github.com/winnow-rs/winnow/discussions)
+//! - [CHANGELOG](https://github.com/winnow-rs/winnow/blob/v1.0.0/CHANGELOG.md) (includes major version migration
+//!   guides)
+//!
+//! ## Aspirations
+//!
+//! `winnow` aims to be your "do everything" parser, much like people treat regular expressions.
+//!
+//! In roughly priority order:
+//! 1. Support writing parser declaratively while not getting in the way of imperative-style
+//!    parsing when needed, working as an open-ended toolbox rather than a close-ended framework.
+//! 2. Flexible enough to be used for any application, including parsing strings, binary data,
+//!    or separate [lexing and parsing phases][_topic::lexing]
+//! 3. Zero-cost abstractions, making it easy to write high performance parsers
+//! 4. Easy to use, making it trivial for one-off uses
+//!
+//! In addition:
+//! - Resilient maintainership, including
+//!   - Willing to break compatibility rather than batching up breaking changes in large releases
+//!   - Leverage feature flags to keep one active branch
+//! - We will support the last 6 months of rust releases (MSRV)
+//!
+//! See also [Special Topic: Why winnow?][crate::_topic::why]
+//!
+//! ## Example
+//!
+//! Run
+//! ```console
+//! $ cargo add winnow
+//! ```
+//!
+//! Then use it to parse:
+//! ```rust
+//! # #[cfg(all(feature = "alloc", feature = "parser"))] {
+#![doc = include_str!("../examples/css/parser.rs")]
+//! # }
+//! ```
+//!
+//! See also the [Tutorial][_tutorial::chapter_0] and [Special Topics][_topic]
+
+#![cfg_attr(docsrs, feature(doc_cfg))]
+#![cfg_attr(docsrs, feature(extended_key_value_attributes))]
+#![cfg_attr(all(not(feature = "std"), not(test)), no_std)]
+#![warn(missing_docs)]
+#![warn(clippy::std_instead_of_core)]
+#![warn(clippy::std_instead_of_alloc)]
+#![warn(clippy::print_stderr)]
+#![warn(clippy::print_stdout)]
+
+#[cfg(feature = "alloc")]
+#[cfg_attr(test, macro_use)]
+#[allow(unused_extern_crates)]
+extern crate alloc;
+
+#[doc = include_str!("../README.md")]
+#[cfg(doctest)]
+pub struct ReadmeDoctests;
+
+pub(crate) mod util {
+    #[allow(dead_code)]
+    pub(crate) fn from_fn<F: Fn(&mut core::fmt::Formatter<'_>) -> core::fmt::Result>(
+        f: F,
+    ) -> FromFn<F> {
+        FromFn(f)
+    }
+
+    pub(crate) struct FromFn<F>(F)
+    where
+        F: Fn(&mut core::fmt::Formatter<'_>) -> core::fmt::Result;
+
+    impl<F> core::fmt::Debug for FromFn<F>
+    where
+        F: Fn(&mut core::fmt::Formatter<'_>) -> core::fmt::Result,
+    {
+        fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+            (self.0)(f)
+        }
+    }
+
+    impl<F> core::fmt::Display for FromFn<F>
+    where
+        F: Fn(&mut core::fmt::Formatter<'_>) -> core::fmt::Result,
+    {
+        fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+            (self.0)(f)
+        }
+    }
+}
+
+#[macro_use]
+mod macros;
+
+#[macro_use]
+#[cfg(feature = "parser")]
+pub mod error;
+
+#[cfg(feature = "parser")]
+mod parser;
+
+pub mod stream;
+
+#[cfg(feature = "ascii")]
+pub mod ascii;
+#[cfg(feature = "binary")]
+pub mod binary;
+#[cfg(feature = "parser")]
+pub mod combinator;
+#[cfg(feature = "parser")]
+pub mod token;
+
+#[cfg(feature = "unstable-doc")]
+pub mod _topic;
+#[cfg(feature = "unstable-doc")]
+pub mod _tutorial;
+
+/// Core concepts available for glob import
+///
+/// Including
+/// - [`StreamIsPartial`][crate::stream::StreamIsPartial]
+/// - [`Parser`]
+///
+/// ## Example
+///
+/// ```rust
+/// # #[cfg(feature = "ascii")] {
+/// use winnow::prelude::*;
+///
+/// fn parse_data(input: &mut &str) -> ModalResult<u64> {
+///     // ...
+/// #   winnow::ascii::dec_uint(input)
+/// }
+///
+/// fn main() {
+///   let result = parse_data.parse("100");
+///   assert_eq!(result, Ok(100));
+/// }
+/// # }
+/// ```
+pub mod prelude {
+    #[cfg(feature = "parser")]
+    pub use crate::error::ModalError as _;
+    #[cfg(feature = "parser")]
+    pub use crate::error::ParserError as _;
+    pub use crate::stream::AsChar as _;
+    pub use crate::stream::ContainsToken as _;
+    pub use crate::stream::Stream as _;
+    pub use crate::stream::StreamIsPartial as _;
+    #[cfg(feature = "parser")]
+    pub use crate::ModalParser;
+    #[cfg(feature = "parser")]
+    pub use crate::ModalResult;
+    #[cfg(feature = "parser")]
+    pub use crate::Parser;
+    #[cfg(feature = "unstable-recover")]
+    #[cfg(feature = "std")]
+    #[cfg(feature = "parser")]
+    pub use crate::RecoverableParser as _;
+
+    #[cfg(all(test, feature = "parser"))]
+    pub(crate) use crate::TestResult;
+}
+
+#[cfg(feature = "parser")]
+pub use error::ModalResult;
+#[cfg(feature = "parser")]
+pub use error::Result;
+#[cfg(feature = "unstable-recover")]
+#[cfg(feature = "std")]
+#[cfg(feature = "parser")]
+pub use parser::RecoverableParser;
+#[cfg(feature = "parser")]
+pub use parser::{ModalParser, Parser};
+pub use stream::BStr;
+pub use stream::Bytes;
+pub use stream::LocatingSlice;
+pub use stream::Partial;
+pub use stream::Stateful;
+pub use stream::Str;
+
+#[cfg(all(test, feature = "parser"))]
+pub(crate) use error::TestResult;