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/embedded-graphics-core/CHANGELOG.md

@@ -0,0 +1,105 @@
+# Changelog
+
+`embedded-graphics-core` changelog.
+
+<!-- next-header -->
+
+## [Unreleased] - ReleaseDate
+
+## [0.4.1] - 2026-02-15
+
+### Changed
+
+- (technically breaking) [#731](https://github.com/embedded-graphics/embedded-graphics/pull/731) Bump MSRV to 1.71.1
+
+### Fixed
+
+- [#806](https://github.com/embedded-graphics/embedded-graphics/pull/806) Fixed build on MSRV by using tighter dependencies.
+
+## [0.4.0] - 2023-05-14
+
+### Added
+
+- [#612](https://github.com/embedded-graphics/embedded-graphics/pull/612), [#699](https://github.com/embedded-graphics/embedded-graphics/pull/699) Added `GetPixel` trait.
+- [#625](https://github.com/embedded-graphics/embedded-graphics/pull/625) Added CSS colors and color conversions to `Rgb666` and `Bgr666`.
+- [#656](https://github.com/embedded-graphics/embedded-graphics/pull/656) Added `Rgb666` and `Bgr666` conversions.
+- [#710](https://github.com/embedded-graphics/embedded-graphics/pull/710) Added `AnchorX`, `AnchorY`, `AnchorPoint::x`, `AnchorPoint::y` and `AnchorPoint::from_xy`.
+- [#710](https://github.com/embedded-graphics/embedded-graphics/pull/710) Added `Rectangle::resized_width`, `Rectangle::resized_height`, `Rectangle::anchor_x` and `Rectangle::anchor_y`.
+
+### Changed
+
+- **(breaking)** [#660](https://github.com/embedded-graphics/embedded-graphics/pull/660) Remove `RawU18` color storage type and use `RawU24` in is place for `Rgb666` and `Bgr666`.
+- [#651](https://github.com/embedded-graphics/embedded-graphics/pull/651), [#652](https://github.com/embedded-graphics/embedded-graphics/pull/652) Improved performance of color conversions.
+- **(breaking)** [#663](https://github.com/embedded-graphics/embedded-graphics/pull/663) Upgraded Cargo dependencies to their latest versions.
+- **(breaking)** [#689](https://github.com/embedded-graphics/embedded-graphics/pull/689) Bump Minimum Supported Rust Version (MSRV) to 1.61.
+
+## [0.3.3] - 2021-09-09
+
+### Added
+
+- [#621](https://github.com/embedded-graphics/embedded-graphics/pull/621) Added `Rgb666` and `Bgr666` color type support.
+
+## [0.3.2] - 2021-06-05
+
+### Added
+
+- [#602](https://github.com/embedded-graphics/embedded-graphics/pull/602) Implemented `core::fmt::Display` for `Point` and `Size`.
+
+## [0.3.1] - 2021-05-03
+
+### Added
+
+- [#589](https://github.com/embedded-graphics/embedded-graphics/pull/589) Implemented `From` trait to convert from RGB colors to grayscale colors, between different grayscale colors and from grayscale and RGB colors to `BinaryColor`.
+
+## [0.3.0] - 2021-04-19
+
+### Added
+
+- **(breaking)** [#552](https://github.com/embedded-graphics/embedded-graphics/pull/552) Added the `Output` associated type to `Drawable` to allow returning non-`()` values from drawing operations.
+- [#563](https://github.com/embedded-graphics/embedded-graphics/pull/563) Added `is_none`, `is_text_color` and `is_custom` methods to `DecorationColor`.
+
+### Removed
+
+- **(breaking)** [#569](https://github.com/embedded-graphics/embedded-graphics/pull/569) Removed text renderer API. The text renderer API will be added back when it has stabilized.
+- **(breaking)** [#572](https://github.com/embedded-graphics/embedded-graphics/pull/572) Moved `pixelcolor::raw::RawDataIter` into `embedded-graphics` crate.
+
+### Fixed
+
+- [#571](https://github.com/embedded-graphics/embedded-graphics/pull/571) `Rectangle::points` did return a non empty iterator for rectangles with zero width.
+
+## [0.2.0] - 2021-02-03
+
+### Added
+
+- [#523](https://github.com/embedded-graphics/embedded-graphics/pull/523) Added the external text renderer API.
+
+### Removed
+
+- [#522](https://github.com/embedded-graphics/embedded-graphics/pull/522) The `draw_target` module, expect the `DrawTarget` trait, was moved to `embedded-graphics`.
+- [#522](https://github.com/embedded-graphics/embedded-graphics/pull/522) The `iterator` module was moved to `embedded-graphics`.
+
+## [0.1.1] - 2020-12-07
+
+### Added
+
+- [#514](https://github.com/embedded-graphics/embedded-graphics/pull/514) Add `ImageDrawable` to the `prelude`.
+
+## [0.1.0] - 2020-11-29
+
+### Added
+
+- [#498](https://github.com/embedded-graphics/embedded-graphics/pull/498) Split common functionality out of `embedded-graphics` into `embedded-graphics-core`.
+- [#498](https://github.com/embedded-graphics/embedded-graphics/pull/498) Added `Size::saturating_add` and `Size::saturating_sub`.
+
+<!-- next-url -->
+[unreleased]: https://github.com/embedded-graphics/embedded-graphics-core/compare/embedded-graphics-core-v0.4.1...HEAD
+[0.4.1]: https://github.com/embedded-graphics/embedded-graphics-core/compare/embedded-graphics-core-v0.4.0...embedded-graphics-core-v0.4.1
+[0.4.0]: https://github.com/embedded-graphics/embedded-graphics-core/compare/embedded-graphics-core-v0.3.3...embedded-graphics-core-v0.4.0
+[0.3.3]: https://github.com/embedded-graphics/embedded-graphics-core/compare/embedded-graphics-core-v0.3.2...embedded-graphics-core-v0.3.3
+[0.3.2]: https://github.com/embedded-graphics/embedded-graphics-core/compare/embedded-graphics-core-v0.3.1...embedded-graphics-core-v0.3.2
+[0.3.1]: https://github.com/embedded-graphics/embedded-graphics-core/compare/embedded-graphics-core-v0.3.0...embedded-graphics-core-v0.3.1
+
+[0.3.0]: https://github.com/embedded-graphics/embedded-graphics-core/compare/embedded-graphics-core-v0.2.0...embedded-graphics-core-v0.3.0
+[0.2.0]: https://github.com/embedded-graphics/embedded-graphics-core/compare/embedded-graphics-core-v0.1.1...embedded-graphics-core-v0.2.0
+[0.1.1]: https://github.com/embedded-graphics/embedded-graphics-core/compare/embedded-graphics-core-v0.1.0...embedded-graphics-core-v0.1.1
+[0.1.0]: https://github.com/embedded-graphics/embedded-graphics/compare/embedded-graphics-v0.7.0-alpha.1...embedded-graphics-core-v0.1.0