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-hal-nb/CHANGELOG.md

@@ -0,0 +1,59 @@
+# Change Log
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/)
+and this project adheres to [Semantic Versioning](http://semver.org/).
+
+## [Unreleased]
+
+No unreleased changes
+
+## [v1.0.0] - 2023-12-28
+
+- Updated `embedded-hal` to version `1.0.0`.
+
+## [v1.0.0-rc.3] - 2023-12-14
+
+- Updated `embedded-hal` to version `1.0.0-rc.3`.
+
+## [v1.0.0-rc.2] - 2023-11-28
+
+- Updated `embedded-hal` to version `1.0.0-rc.2`.
+- Minor document fixes.
+- Add #[inline] hints to most of `embedded-hal-nb` functions.
+
+## [v1.0.0-rc.1] - 2023-08-15
+
+- Updated `embedded-hal` to version `1.0.0-rc.1`.
+- Added `+ ?Sized` to all blanket impls.
+
+## [v1.0.0-alpha.3] - 2023-07-04
+
+### Changed
+- Updated `embedded-hal` to version `1.0.0-alpha.11`.
+
+
+## [v1.0.0-alpha.2] - 2023-04-04
+
+### Changed
+- Updated `embedded-hal` to version `1.0.0-alpha.10`.
+
+## [v1.0.0-alpha.1] - 2022-09-28
+
+### Changed
+- Updated `embedded-hal` to version `1.0.0-alpha.9`.
+
+## [v1.0.0-alpha.0] - 2022-09-27
+
+First release to crates.io
+
+[Unreleased]: https://github.com/rust-embedded/embedded-hal/compare/embedded-hal-nb-v1.0.0...HEAD
+[v1.0.0]: https://github.com/rust-embedded/embedded-hal/compare/embedded-hal-nb-v1.0.0-rc.3...embedded-hal-nb-v1.0.0
+[v1.0.0-rc.3]: https://github.com/rust-embedded/embedded-hal/compare/embedded-hal-nb-v1.0.0-rc.2...embedded-hal-nb-v1.0.0-rc.3
+[v1.0.0-rc.2]: https://github.com/rust-embedded/embedded-hal/compare/embedded-hal-nb-v1.0.0-rc.1...embedded-hal-nb-v1.0.0-rc.2
+[v1.0.0-rc.1]: https://github.com/rust-embedded/embedded-hal/compare/embedded-hal-nb-v1.0.0-alpha.3...embedded-hal-nb-v1.0.0-rc.1
+[v1.0.0-alpha.3]: https://github.com/rust-embedded/embedded-hal/compare/embedded-hal-nb-v1.0.0-alpha.2...embedded-hal-nb-v1.0.0-alpha.3
+[v1.0.0-alpha.2]: https://github.com/rust-embedded/embedded-hal/compare/embedded-hal-nb-v1.0.0-alpha.1...embedded-hal-nb-v1.0.0-alpha.2
+[v1.0.0-alpha.1]: https://github.com/rust-embedded/embedded-hal/compare/embedded-hal-nb-v1.0.0-alpha.0...embedded-hal-nb-v1.0.0-alpha.1
+[v1.0.0-alpha.0]: https://github.com/rust-embedded/embedded-hal/tree/embedded-hal-nb-v1.0.0-alpha.0