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/embassy-nrf/CHANGELOG.md

@@ -0,0 +1,53 @@
+# Changelog for embassy-nrf
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## Unreleased
+
+## 0.2.0 - 2024-08-05
+
+- Support for NRF chips:
+  - nrf51
+  - nrf9151
+- Support for new peripherals:
+  - EGU
+  - radio - low-level support for IEEE 802.15.4 and BLE via radio peripheral
+- Peripheral changes:
+  - gpio: Drop GPIO Pin generics (API break)
+  - pdm: Fix gain register value derivation
+  - pwm:
+    - Expose `duty` method
+    - Expose `pwm::PWM_CLK_HZ` and add `is_enabled` method
+    - Allow specifying OutputDrive for PWM channels
+    - Fix infinite loop
+  - spim:
+    - Reduce trace-level messages ("Copying SPIM tx buffer..")
+    - Support configuring bit order for bus
+    - Allow specifying OutputDrive for SPI pins
+    - Add bounds checks for EasyDMA buffer size
+    - Implement chunked DMA transfers
+  - uart:
+    - Add support for rx- or tx-only BufferedUart
+    - Implement splitting Rx/Tx
+    - Add support for handling RX errors
+- Miscellaneous changes:
+  - Add `collapse_debuginfo` to fmt.rs macros.
+  - Drop `sealed` mod
+  - nrf52840: Add dcdc voltage parameter to configure REG0 regulator
+
+## 0.1.0 - 2024-01-12
+
+- First release with support for following NRF chips:
+  - nrf52805
+  - nrf52810
+  - nrf52811
+  - nrf52820
+  - nrf52832
+  - nrf52833
+  - nrf52840
+  - nrf5340
+  - nrf9160
+