feat: 底部控制栏添加摄像头/麦克风开关，说话时麦克风脉冲动画

- useVisionSession 新增 isCameraOn/isMicOn 状态 + toggleCamera/toggleMic
- 底部控制栏添加 📷🎤 图标按钮，开启绿色/关闭红色
- 说话时麦克风按钮绿色脉冲缩放动画（micPulse）
- 按钮样式优化：nowrap 防换行，flex-wrap 自适应

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/src/hooks/useVisionSession.ts

@@ -36,6 +36,8 @@ export function useVisionSession() {
   const [config, setConfig] = useState<SessionConfig>(loadConfig);
   const [stats, setStats] = useState<SessionStats>({ queryCount: 0, totalTokens: 0 });
   const [mode, setMode] = useState<SessionMode>("dialogue");
+  const [isCameraOn, setIsCameraOn] = useState(false);
+  const [isMicOn, setIsMicOn] = useState(false);
 
   // 上一帧采样数据（用于关键帧检测）
   const prevFrameRef = useRef<Uint8ClampedArray | null>(null);
@@ -280,11 +282,13 @@ export function useVisionSession() {
   const startSession = useCallback(async () => {
     // 1. 获取摄像头和麦克风
     await startCamera();
+    setIsCameraOn(true);
     const micStream = await startMic();
     if (!micStream) {
       showToast("无法获取麦克风权限", "error");
       return;
     }
+    setIsMicOn(true);
 
     // 2. 连接 WebSocket
     connect();
@@ -310,8 +314,32 @@ export function useVisionSession() {
     setStats({ queryCount: 0, totalTokens: 0 });
     historyRef.current = [];
     prevFrameRef.current = null;
+    setIsCameraOn(false);
+    setIsMicOn(false);
   }, [stopObserving, stopVAD, stopMic, stopCamera, disconnect]);
 
+  /** 摄像头开关 */
+  const toggleCamera = useCallback(async () => {
+    if (isCameraOn) {
+      stopCamera();
+      setIsCameraOn(false);
+    } else {
+      await startCamera();
+      setIsCameraOn(true);
+    }
+  }, [isCameraOn, startCamera, stopCamera]);
+
+  /** 麦克风开关 */
+  const toggleMic = useCallback(async () => {
+    if (isMicOn) {
+      stopMic();
+      setIsMicOn(false);
+    } else {
+      const micStream = await startMic();
+      setIsMicOn(!!micStream);
+    }
+  }, [isMicOn, startMic, stopMic]);
+
   /** 打断当前回复 */
   const interrupt = useCallback(() => {
     send({ type: "interrupt" });
@@ -351,5 +379,9 @@ export function useVisionSession() {
     startSession,
     stopSession,
     interrupt,
+    isCameraOn,
+    isMicOn,
+    toggleCamera,
+    toggleMic,
   };
 }