feat(remote): 修复键盘输入映射并重构连接流程

- Android端注入按键时显式设置SOURCE_KEYBOARD，修复IME丢弃事件导致输入框无法输入文字的问题
- Flutter端新增Flutter逻辑键到Android keyCode的转换映射，避免功能键误触发
- 重构RemoteController，分离信令连接与远程控制逻辑，支持设备列表选择与配对码兑换
- AuthRepository接口新增getBindings、getOnlineDevices、redeemPairingCode方法
- DioAuthRepository实现401自动刷新token重试机制
- ConnectionSessionState扩展设备列表、在线状态、配对码等状态字段

webrtc_controller_flutter/lib/l10n/app_en.arb

@@ -13,8 +13,7 @@
   "connecting": "Connecting...",
   "loginAccount": "Login Account",
   "connectDevice": "Connect Device",
-  "serverUrl": "Signal Server URL:",
-  "serverUrlPlaceholder": "wss://www.ttstd.com/signal",
+
   "deviceId": "Device ID (assigned by server):",
   "deviceIdPlaceholder": "Assigned by server",
   "targetDeviceId": "Target Device ID:",
@@ -23,7 +22,7 @@
   "password": "Password",
   "loginFailed": "Login failed: {error}",
   "usernamePasswordRequired": "Please enter username and password",
-  "serverAndTargetRequired": "Please enter server URL and target device ID",
+  "targetRequired": "Please enter target device ID",
   "authTitle": "Connection Auth",
   "authNone": "Passwordless",
   "authNoneDesc": "Manual confirmation on the controlled device",
@@ -67,5 +66,16 @@
   "forceLogout": "Account logged in elsewhere, force logged out.",
   "loginFirst": "Please login before connecting",
   "pleaseFillAuth": "Please enter the code or password",
-  "streamModeSelfCodecDesc": "Self-codec hardware decoding is not supported on this platform."
+  "streamModeSelfCodecDesc": "Self-codec hardware decoding is not supported on this platform.",
+  "boundDevices": "Bound Devices",
+  "online": "Online",
+  "offline": "Offline",
+  "noBoundDevices": "No bound devices yet",
+  "refreshDevices": "Refresh",
+  "redeemPairingCode": "Bind with Pairing Code",
+  "pairingCodeHint": "Enter the pairing code shown on the controlled device",
+  "bindingFailed": "Binding failed: {error}",
+  "deviceOfflineCannotConnect": "Device \"{name}\" is currently offline and cannot be connected",
+  "pleaseSelectDevice": "Please select a bound device first",
+  "bindSuccess": "Bound successfully"
 }