Improvements for bluetooth stabiltiy

[Amueller36]

What & why

Improves Bluetooth connection stability and recovery, and adds diagnostics for investigating intermittent PC disconnects.

• Fixes a race where a Ride disconnect during setup sometimes clears pointers while they were still being used, sometimes leading to crash the ESP32 and dropping both Bluetooth links.
• Reuses the BLE client and a static callback to eliminate the per reconnect callback leak.
• Checks the RideOn handshake, notification descriptor, and subscription before marking the Ride ready.
• Moves scan/reconnect control into the main loop, with finite scans, retry backoff, and disconnect-completion handling.
• Clears stale button state when the Ride disconnects.
• Adds separate PC and Ride disconnect logs, PC connection/security information, boot reset reasons, and diagnostics for the heap
• Pins PlatformIO dependencies for reproducible builds

No related issue.

Tested on

• Board: ESP32-S3, revision v0.2, with 8 MB embedded PSRAM; built using the esp32-s3-devkitc-1 PlatformIO configuration with PSRAM disabled.
• Core / library versions:
  • PlatformIO Espressif32 platform: 6.12.0
  • Arduino-ESP32 core: 2.0.17
  • NimBLE-Arduino: 2.5.1
  • ESPAsyncWebServer: 3.12.0
  • AsyncTCP: 3.5.0
  • ESP32 NIMBLE Keyboard: 2.0.1, commit 1f04c0496a398924bf321d7b27956beab485deb2
• End device + app: Intended for PC Bluetooth HID use with MyWhoosh; end-to-end app testing and reconnect stability testing are not yet confirmed.

PlatformIO firmware build passed and firmware was flashed to the physical ESP32-S3

Checklist

• Builds in Arduino IDE (ESP32-S3, core 3.x)
• Tested on real hardware (or marked as untested): flashed successfully; functional and stability testing remain unverified as noted above.
• No second BLE/Bluedroid keyboard library pulled in
• UI strings added to both en.json and de.json (if applicable): not applicable; no UI strings changed.
• No vendor/AI attribution added to commits or docs