feat: add Android USB serial port support via USB Host API

- Add USB Host permissions and device filter to AndroidManifest.xml
- Create UsbSerialPlugin Kotlin plugin for USB Host API (enumerate, permission, open devices)
- Add serial_connect_fd command for Android to accept USB file descriptors
- Create RawFdStream wrapper for async I/O on raw file descriptors
- Make run_serial_with_poll generic over AsyncRead+AsyncWrite
- Register UsbSerialPlugin in MainActivity

src-tauri/tauri.conf.json

@@ -45,15 +45,5 @@
       "resources/je-skin-devkit-server.exe"
     ]
   },
-  "plugins": {
-    "updater": {
-      "windows": {
-        "installMode": "passive"
-      },
-      "pubkey": "dW50cnVzdGVkIGNvbW1lbnQ6IG1pbmlzaWduIHB1YmxpYyBrZXk6IDkwODM1QkFEODI2NkZENgpSV1RXYnliWXVqVUlDUVRxbjlseDNDNjhQTGpDYis4TEZMeUk2WVhiMEhTRWJhN3hGRnQ3TTJtcwo=",
-      "endpoints": [
-        "https://je-skin.cn-nb1.rains3.com/latest.json"
-      ]
-    }
-  }
+  "plugins": {}
 }