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/bare-metal/CHANGELOG.md

@@ -0,0 +1,87 @@
+# Change Log
+
+All notable changes to this project will be documented in this file.
+This project adheres to [Semantic Versioning](http://semver.org/).
+
+## [Unreleased]
+
+## [v1.0.0] - 2020-06-23
+
+### Breaking Changes
+
+- Use `CriticalSection<'cs>` everywhere instead of `&'cs CriticalSection`
+  (this makes it a zero-sized type).
+- Removed the `const-fn` feature.
+- Removed the `Peripheral` wrapper type.
+
+## [v0.2.5] - 2019-08-29
+
+### Changed
+
+- The `const-fn` feature is now stable.
+
+## [v0.2.4] - 2018-10-30
+
+### Added
+
+- Note in the documentation that `Mutex` is not memory safe in multi-core systems.
+
+### Changed
+
+- The `const-fn` feature can now be used on 1.31-beta and will also work on stable 1.31.
+
+## [v0.2.3] - 2018-08-17
+
+### Fixed
+
+- A compilation error when using a recent nightly while the "const-fn" feature was enabled.
+
+## [v0.2.2] - 2018-08-17 - YANKED
+
+### Fixed
+
+- A compilation error when using a recent nightly while the "const-fn" feature was enabled.
+
+## [v0.2.1] - 2018-08-03
+
+### Fixed
+
+- Soundness issue where it was possible to borrow the contents of a Mutex for longer than the
+  lifetime of the Mutex.
+
+## [v0.2.0] - 2018-05-10 - YANKED
+
+YANKED due to a soundness issue: see v0.2.1 for details
+
+### Changed
+
+- [breaking-change] `const-fn` is no longer a default feature (i.e. a feature that's enabled by
+  default). The consequence is that this crate now compiles on 1.27 (beta) by default, and opting
+  into `const-fn` requires nightly.
+
+## [v0.1.2] - 2018-04-24
+
+### Added
+
+- An opt-out "const-fn" Cargo feature. When this feature is disabled this crate compiles on stable.
+
+## [v0.1.1] - 2017-09-19
+
+### Fixed
+
+- Added feature gate to make this work on recent nightlies
+
+## v0.1.0 - 2017-07-06
+
+- Initial release
+
+[Unreleased]: https://github.com/japaric/bare-metal/compare/v1.0.0...HEAD
+[v1.0.0]: https://github.com/japaric/bare-metal/compare/v0.2.5...v1.0.0
+[v0.2.5]: https://github.com/japaric/bare-metal/compare/v0.2.4...v0.2.5
+[v0.2.4]: https://github.com/japaric/bare-metal/compare/v0.2.3...v0.2.4
+[v0.2.3]: https://github.com/japaric/bare-metal/compare/v0.2.2...v0.2.3
+[v0.2.2]: https://github.com/japaric/bare-metal/compare/v0.2.1...v0.2.2
+[v0.2.1]: https://github.com/japaric/bare-metal/compare/v0.2.0...v0.2.1
+[v0.2.0]: https://github.com/japaric/bare-metal/compare/v0.1.2...v0.2.0
+[v0.1.2]: https://github.com/japaric/bare-metal/compare/v0.1.1...v0.1.2
+[v0.1.1]: https://github.com/japaric/bare-metal/compare/v0.1.0...v0.1.1