feat(bridge): add wifi/serial bridge runtime and UI

Co-authored-by: Cursor <cursoragent@cursor.com>

bridge-serial/README.md

@@ -0,0 +1,19 @@
+# bridge-serial
+
+ESP32 ESP-NOW bridge with **USB/serial** uplink to the Pi (GPIO UART). Sync loop only — no asyncio, no Microdot.
+
+```
+bridge-serial/
+  src/
+    main.py       # entry
+    settings.py   # /settings.json on device
+```
+
+Deploy:
+
+```bash
+cd bridge-serial
+python ../led-tool/cli.py -p /dev/ttyUSB0 --src -r -f
+```
+
+No `--lib` required. Match `serial_baudrate` on the ESP and Pi (e.g. `921600`).