feat(matter): add local Matter bridge for Google Home

[ashworth3]

Summary

• Add an in-process Matter aggregator bridge so WeMo switches/plugs can be controlled from Google Home, Apple Home, and Alexa on the local network
• Extract DeviceService so REST and Matter share discovery, control, and state events
• Add PWA Settings → Google Home & Matter (enable/disable, pairing QR/code, auto device-type mapping with optional override)
• Document setup and troubleshooting in docs/GOOGLE-HOME.md and component design in docs/MATTER.md

Test plan

• bun run lint / bun run typecheck / bun run test pass
• Enable Matter in Settings → Google Home & Matter; status shows devices as Plug or Light
• Register VID/PID in Google Home Developer Console (0xFFF1 / 0x8001)
• Pair via QR; Nest Matter hub on same Wi-Fi
• Toggle from Google Home home/room tile (not the device settings page)
• Control from Open Wemo PWA still works and stays in sync
• Reset pairing and re-pair works after a failed attempt

Notes for reviewers

• Google Home requires a Nest Matter hub and a one-time Developer Console integration for uncertified VID/PID (documented)
• Matter persistence uses SQLite under Bun on Windows to avoid file-driver EPERM issues