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/esp-synopsys-usb-otg/CHANGELOG.md

@@ -0,0 +1,27 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
+and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+
+### Changed
+
+* Use `critical-section` crate for critical sections.
+* Replaced bundled RAL macros with `ral-registers`
+
+
+## [v0.4.0] - 2023-11-18
+
+### Changed
+
+* `usb-device` version bumped to v0.3.0
+
+
+
+[Unreleased]: https://github.com/stm32-rs/synopsys-usb-otg/compare/v0.4.0...HEAD
+[0.4.0]: https://github.com/stm32-rs/synopsys-usb-otg/compare/v0.4.0...v0.3.2
+[0.3.2]: https://github.com/stm32-rs/synopsys-usb-otg/compare/v0.3.2...v0.3.1