fix(call): 添加通话权限检查机制

- 在发起和接听通话前添加权限检查，确保有相应权限才能进行通话
- 根据通话类型区分视频通话(3)和语音通话(2)的权限验证
- 修复直播间上麦权限检查逻辑，区分嘉宾和普通观众的不同权限需求
- 为普通观众上麦单独实现麦克风权限检查方法
- 修复余额显示逻辑，当可用余额和单位销售余额都为0时隐藏余额显示

lib/controller/discover/room_controller.dart

@@ -238,8 +238,19 @@ class RoomController extends GetxController with WidgetsBindingObserver {
   }
 
   Future<void> joinChat(CurrentRole role) async {
-    final granted = await _ensureRtcPermissions();
-    if (!granted) return;
+    // 根据角色检查权限：男/女嘉宾需要摄像头和麦克风权限，普通观众只需要麦克风权限
+    bool granted = false;
+    if (role == CurrentRole.maleAudience || role == CurrentRole.femaleAudience) {
+      // 男/女嘉宾上麦：需要摄像头和麦克风权限
+      granted = await _ensureRtcPermissions();
+    } else {
+      // 普通观众上麦：只需要麦克风权限
+      granted = await _ensureMicrophonePermission();
+    }
+    if (!granted) {
+      print('❌ [RoomController] 权限检查失败，无法上麦');
+      return;
+    }
     final data = {
       'channelId': RTCManager.instance.currentChannelId,
       'seatNumber': role == CurrentRole.maleAudience ? 1 : 2,
@@ -374,6 +385,22 @@ class RoomController extends GetxController with WidgetsBindingObserver {
     return false;
   }
 
+  /// 检查麦克风权限（用于普通观众上麦）
+  Future<bool> _ensureMicrophonePermission() async {
+    final micStatus = await Permission.microphone.request();
+    if (micStatus.isGranted) {
+      return true;
+    }
+    
+    if (micStatus.isPermanentlyDenied) {
+      SmartDialog.showToast('请在系统设置中开启麦克风权限');
+      await openAppSettings();
+    } else {
+      SmartDialog.showToast('请允许麦克风权限以进入房间');
+    }
+    return false;
+  }
+
   Future<void> leaveChannel() async {
     if (currentRole == CurrentRole.broadcaster) {
       try {

lib/controller/message/call_controller.dart

@@ -236,6 +236,14 @@ class CallController extends GetxController {
       return false;
     }
 
+    // 先检查权限，没有权限不能进行下一步
+    final type = callType == CallType.video ? 3 : 2; // 2=语音通话，3=视频通话
+    final hasPermission = await _ensureCallPermissions(type);
+    if (!hasPermission) {
+      print('❌ [CallController] 权限检查失败，无法发起通话');
+      return false;
+    }
+
     // 检查是否在直播间
     try {
       if (Get.isRegistered<RoomController>()) {
@@ -259,7 +267,6 @@ class CallController extends GetxController {
     );
 
     // 发起通话前，先创建一对一 RTC 频道
-    final type = callType == CallType.video ? 3 : 2; // 1为音频，2为视频
     final channelData = await createOneOnOneRtcChannel(
       type: type,
       toUserId: targetUserId,
@@ -361,6 +368,14 @@ class CallController extends GetxController {
       '📞 [CallController] 接听${callType == CallType.video ? "视频" : "语音"}通话',
     );
 
+    // 先检查权限，没有权限不能进行下一步
+    final type = callType == CallType.video ? 3 : 2; // 2=语音通话，3=视频通话
+    final hasPermission = await _ensureCallPermissions(type);
+    if (!hasPermission) {
+      print('❌ [CallController] 权限检查失败，无法接听通话');
+      return false;
+    }
+
     // 清空之前的远端用户UID和通话信息
     remoteUid.value = null;
     _callChannelId = null;

lib/pages/message/video_call_page.dart

@@ -585,9 +585,11 @@ class _VideoCallPageState extends State<VideoCallPage> {
                 return const SizedBox.shrink();
               }
               
-              final availableBalance = consumeData?.availableBalance ?? 44;
-              final unitSellingBalance = consumeData?.unitSellingBalance ?? 35;
-              
+              final availableBalance = consumeData?.availableBalance ?? 0;
+              final unitSellingBalance = consumeData?.unitSellingBalance ?? 0;
+              if (availableBalance <= 0 && unitSellingBalance <= 0) {
+                return SizedBox();
+              }
               return Center(
                 child: Text(
                   '玫瑰剩余$availableBalance支($unitSellingBalance玫瑰/分钟)',