Add support for image input in model resources and enhance related configurations

- Introduce a new `support_image_input` field in model resources, allowing models to indicate support for image input.
- Update the backend models, schemas, and database seed scripts to accommodate the new field.
- Enhance the AssistantConfig and related routes to handle image input capabilities, ensuring proper validation and error handling.
- Modify the frontend components to include toggles for enabling visual understanding and filtering models based on image input support.
- Implement necessary adjustments in the voice preview and pipeline to integrate video stream handling alongside audio functionalities.

frontend/src/hooks/use-camera-preview.ts

@@ -3,9 +3,8 @@
 /**
  * 摄像头预览:纯前端 getUserMedia 视频流,供调试抽屉的「视频流」视图使用。
  *
- * 与 use-voice-preview 分离:麦克风/语音会话走 WebRTC 到后端,摄像头目前只在
- * 本地预览。后续接入视觉理解管线时,把这条 video track 加进现有 PeerConnection
- * (pc.addTrack)并在后端 transport 打开 video_in_enabled 即可。
+ * 与 use-voice-preview 分离:这里负责摄像头设备枚举与本地预览;开始视觉会话时,
+ * 调用方会把这条 video track 加进语音 WebRTC PeerConnection。
  */
 
 import { useCallback, useEffect, useRef, useState } from "react";
@@ -50,12 +49,12 @@ export function useCameraPreview() {
     setStream(null);
   }, []);
 
-  const start = useCallback(async () => {
-    if (streamRef.current) return;
+  const start = useCallback(async (): Promise<MediaStream | null> => {
+    if (streamRef.current) return streamRef.current;
     setError(null);
     if (!window.isSecureContext || !navigator.mediaDevices?.getUserMedia) {
       setError("当前页面无法访问摄像头，请通过 https 或 localhost 访问。");
-      return;
+      return null;
     }
     setStarting(true);
     try {
@@ -66,21 +65,24 @@ export function useCameraPreview() {
       streamRef.current = media;
       setStream(media);
       void refreshCameras();
+      return media;
     } catch (mediaError) {
       setError(cameraErrorMessage(mediaError));
+      return null;
     } finally {
       setStarting(false);
     }
   }, [refreshCameras]);
 
   const selectCamera = useCallback(
-    async (id: string) => {
+    async (id: string): Promise<MediaStream | null> => {
       deviceIdRef.current = id;
       setDeviceId(id);
       if (streamRef.current) {
         stop();
-        await start();
+        return await start();
       }
+      return null;
     },
     [start, stop],
   );