fix(webrtc): 修正ICE服务器配置并增强连接诊断日志

修正Flutter控制端TURN凭据错误，移除不可达的内网地址，新增TCP中继候选与详细的ICE状态/候选日志，以解决iOS模拟器下ICE连接失败问题。

webrtc_controller_flutter/lib/webrtc/webrtc_controller.dart

@@ -110,10 +110,20 @@ class WebRtcController {
       'tcpCandidatePolicy': 'enabled',
     };
 
+    final iceUrls = (kIceServers)
+        .map((e) => '${e['username'] != null ? '(${e['username']})' : ''}${e['urls']}')
+        .join(', ');
+    debugPrint('[WebRtcController] signaling server: ${signaling.serverUrl} | '
+        'deviceId=$deviceId target=$targetDeviceId');
+    debugPrint('[WebRtcController] ICE servers: $iceUrls');
+
     _pc = await createPeerConnection(configuration);
 
     _pc!.onIceCandidate = _onIceCandidate;
     _pc!.onIceConnectionState = _onIceConnectionState;
+    _pc!.onIceGatheringState = (state) {
+      debugPrint('[WebRtcController] ICE gathering state: $state');
+    };
     _pc!.onTrack = _onTrack;
     _pc!.onDataChannel = _onDataChannel;
 
@@ -399,6 +409,7 @@ class WebRtcController {
   }
 
   void _onIceCandidate(RTCIceCandidate candidate) {
+    debugPrint('[WebRtcController] local ICE candidate: ${candidate.candidate}');
     final payload = {
       'sdpMid': candidate.sdpMid,
       'sdpMLineIndex': candidate.sdpMLineIndex,
@@ -414,15 +425,39 @@ class WebRtcController {
     signaling.send(msg);
   }
 
+  /// 打印 ICE candidate-pair 统计，用于诊断连接失败原因。
+  Future<void> _dumpIceStats() async {
+    try {
+      final stats = await _pc?.getStats();
+      final pairs = <String>[];
+      for (final report in stats ?? []) {
+        if (report.type == 'candidate-pair') {
+          final state = report.values['state'] ?? report.values['nominated'];
+          pairs.add('${report.values['localCandidateId']}->'
+              '${report.values['remoteCandidateId']} state=$state');
+        }
+      }
+      debugPrint('[WebRtcController] ICE Failed. candidate-pair 数量=${pairs.length}');
+      for (final p in pairs) {
+        debugPrint('[WebRtcController]   pair: $p');
+      }
+    } catch (e) {
+      debugPrint('[WebRtcController] getStats 失败: $e');
+    }
+  }
+
   void _onIceConnectionState(RTCIceConnectionState state) {
     // ignore: avoid_print
     print('ICE connection state: $state');
-    if (state == RTCIceConnectionState.RTCIceConnectionStateConnected) {
+    if (state == RTCIceConnectionState.RTCIceConnectionStateChecking) {
+      debugPrint('[WebRtcController] ICE Checking: 正在收集/交换候选，等待连通...');
+    } else if (state == RTCIceConnectionState.RTCIceConnectionStateConnected) {
       _connectedAt = DateTime.now().millisecondsSinceEpoch;
       onConnectionEstablished?.call();
     } else if (state == RTCIceConnectionState.RTCIceConnectionStateDisconnected) {
       onIceDisconnected?.call('ICE 连接已断开');
     } else if (state == RTCIceConnectionState.RTCIceConnectionStateFailed) {
+      _dumpIceStats();
       onConnectionFailed?.call('ICE 连接失败');
       onDisconnected?.call();
     }
@@ -455,6 +490,7 @@ class WebRtcController {
       payload['sdpMid'] as String?,
       payload['sdpMLineIndex'] as int?,
     );
+    debugPrint('[WebRtcController] remote ICE candidate: ${candidate.candidate}');
     await _pc?.addCandidate(candidate);
   }