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/toml_edit-0.22.27/src/lib.rs

@@ -0,0 +1,149 @@
+//! # `toml_edit`
+//!
+//! This crate allows you to parse and modify toml
+//! documents, while preserving comments, spaces *and
+//! relative order* of items.
+//!
+//! If you also need the ease of a more traditional API, see the [`toml`] crate.
+//!
+//! # Example
+//!
+//! ```rust
+//! # #[cfg(feature = "parse")] {
+//! # #[cfg(feature = "display")] {
+//! use toml_edit::{DocumentMut, value};
+//!
+//! let toml = r#"
+//! "hello" = 'toml!' # comment
+//! ['a'.b]
+//! "#;
+//! let mut doc = toml.parse::<DocumentMut>().expect("invalid doc");
+//! assert_eq!(doc.to_string(), toml);
+//! // let's add a new key/value pair inside a.b: c = {d = "hello"}
+//! doc["a"]["b"]["c"]["d"] = value("hello");
+//! // autoformat inline table a.b.c: { d = "hello" }
+//! doc["a"]["b"]["c"].as_inline_table_mut().map(|t| t.fmt());
+//! let expected = r#"
+//! "hello" = 'toml!' # comment
+//! ['a'.b]
+//! c = { d = "hello" }
+//! "#;
+//! assert_eq!(doc.to_string(), expected);
+//! # }
+//! # }
+//! ```
+//!
+//! ## Controlling formatting
+//!
+//! By default, values are created with default formatting
+//! ```rust
+//! # #[cfg(feature = "display")] {
+//! # #[cfg(feature = "parse")] {
+//! let mut doc = toml_edit::DocumentMut::new();
+//! doc["foo"] = toml_edit::value("bar");
+//! let expected = r#"foo = "bar"
+//! "#;
+//! assert_eq!(doc.to_string(), expected);
+//! # }
+//! # }
+//! ```
+//!
+//! You can choose a custom TOML representation by parsing the value.
+//! ```rust
+//! # #[cfg(feature = "display")] {
+//! # #[cfg(feature = "parse")] {
+//! let mut doc = toml_edit::DocumentMut::new();
+//! doc["foo"] = "'bar'".parse::<toml_edit::Item>().unwrap();
+//! let expected = r#"foo = 'bar'
+//! "#;
+//! assert_eq!(doc.to_string(), expected);
+//! # }
+//! # }
+//! ```
+//!
+//! ## Limitations
+//!
+//! Things it does not preserve:
+//!
+//! * Order of dotted keys, see [issue](https://github.com/toml-rs/toml/issues/163).
+//!
+//! [`toml`]: https://docs.rs/toml/latest/toml/
+
+// https://github.com/Marwes/combine/issues/172
+#![recursion_limit = "256"]
+#![cfg_attr(docsrs, feature(doc_auto_cfg))]
+#![warn(missing_docs)]
+#![warn(clippy::print_stderr)]
+#![warn(clippy::print_stdout)]
+
+mod array;
+mod array_of_tables;
+mod document;
+#[cfg(feature = "display")]
+mod encode;
+mod error;
+mod index;
+mod inline_table;
+mod internal_string;
+mod item;
+mod key;
+#[cfg(feature = "parse")]
+mod parser;
+mod raw_string;
+mod repr;
+mod table;
+mod value;
+
+#[cfg(feature = "serde")]
+pub mod de;
+#[cfg(feature = "serde")]
+pub mod ser;
+
+pub mod visit;
+pub mod visit_mut;
+
+pub use crate::array::{Array, ArrayIntoIter, ArrayIter, ArrayIterMut};
+pub use crate::array_of_tables::{
+    ArrayOfTables, ArrayOfTablesIntoIter, ArrayOfTablesIter, ArrayOfTablesIterMut,
+};
+/// Deprecated, replaced with [`DocumentMut`]
+#[deprecated(since = "0.22.6", note = "Replaced with `DocumentMut`")]
+pub type Document = DocumentMut;
+pub use crate::document::DocumentMut;
+pub use crate::document::ImDocument;
+pub use crate::error::TomlError;
+pub use crate::inline_table::{
+    InlineEntry, InlineOccupiedEntry, InlineTable, InlineTableIntoIter, InlineTableIter,
+    InlineTableIterMut, InlineVacantEntry,
+};
+pub use crate::internal_string::InternalString;
+pub use crate::item::{array, table, value, Item};
+pub use crate::key::{Key, KeyMut};
+pub use crate::raw_string::RawString;
+pub use crate::repr::{Decor, Formatted, Repr};
+pub use crate::table::{
+    Entry, IntoIter, Iter, IterMut, OccupiedEntry, Table, TableLike, VacantEntry,
+};
+pub use crate::value::Value;
+pub use toml_datetime::*;
+
+// Prevent users from some traits.
+pub(crate) mod private {
+    pub trait Sealed {}
+    impl Sealed for usize {}
+    impl Sealed for str {}
+    impl Sealed for String {}
+    impl Sealed for i64 {}
+    impl Sealed for f64 {}
+    impl Sealed for bool {}
+    impl Sealed for crate::Datetime {}
+    impl<T: ?Sized> Sealed for &T where T: Sealed {}
+    impl Sealed for crate::Table {}
+    impl Sealed for crate::InlineTable {}
+}
+
+#[doc = include_str!("../README.md")]
+#[cfg(doctest)]
+#[cfg(feature = "display")]
+#[cfg(feature = "parse")]
+pub struct ReadmeDoctests;