Initial commit: ESP32-C3 WiFi→BLE bridge for Phomemo M110

- BLE client (NimBLE) with auto-scan/reconnect
- ESC/POS protocol encoder (GS v 0 raster)
- Web API: /api/status, /api/connect, /api/print
- Web UI: image upload with dithering, QR codes, positioning
- Client-side QR generation (qrcode-generator)
- Supports bitmap, QR, and raw ESC/POS print types

private_config.ini.example

@@ -0,0 +1,8 @@
+; Example private configuration — copy to private_config.ini and fill in
+; PlatformIO will merge this automatically.
+
+[env:esp32c3]
+build_flags =
+    -DWIFI_SSID='"your-wifi-ssid"'
+    -DWIFI_PASS='"your-wifi-password"'
+    -DPRINTER_BLE_NAME='"Q002E0CP0670069"'