Add limits for content + fix video playback

frontend/src/api/assignments.ts

@@ -32,11 +32,16 @@ export const assignmentsApi = {
     return response.data
   },
 
-  // Get proof image as blob URL
-  getProofImageUrl: async (assignmentId: number): Promise<string> => {
-    const response = await client.get(`/assignments/${assignmentId}/proof-image`, {
+  // Get proof media as blob URL (supports both images and videos)
+  getProofMediaUrl: async (assignmentId: number): Promise<{ url: string; type: 'image' | 'video' }> => {
+    const response = await client.get(`/assignments/${assignmentId}/proof-media`, {
       responseType: 'blob',
     })
-    return URL.createObjectURL(response.data)
+    const contentType = response.headers['content-type'] || ''
+    const isVideo = contentType.startsWith('video/')
+    return {
+      url: URL.createObjectURL(response.data),
+      type: isVideo ? 'video' : 'image',
+    }
   },
 }