feat: add notes_routes.py with robust YouTube duration scraping and background task processing for note generation

src/api/notes_routes.py

@@ -305,10 +305,10 @@ async def process_video_task(task_id: str, youtube_url: str, language: str, user
             if isinstance(seg, dict) and seg.get("key_insight"):
                 key_points_list.append(seg["key_insight"])
 
-        # Step 2: Generate the single primary category (keep in memory)
-        from src.summarization.topic_classifier import get_primary_category
+        # Step 2: Generate the categories (keep in memory)
+        from src.summarization.topic_classifier import classify_topics
         raw_topics = summary_json.get("topics", [])
-        category = get_primary_category(raw_topics) if raw_topics else "Education & Science"
+        categories = classify_topics(raw_topics) if raw_topics else ["Education & Science"]
 
         # Step 3: Combine everything into ONE single dictionary
         note_data = {
@@ -317,7 +317,7 @@ async def process_video_task(task_id: str, youtube_url: str, language: str, user
             "videoTitle": video_title,
             "notes": final_markdown,
             "thumbnail": f"https://img.youtube.com/vi/{video_id}/mqdefault.jpg" if video_id else "",
-            "category": category,
+            "category": categories,
             "keyPoints": key_points_list,
             "createdAt": datetime.utcnow(),
             "updatedAt": datetime.utcnow(),
@@ -328,8 +328,8 @@ async def process_video_task(task_id: str, youtube_url: str, language: str, user
         # The Flutter app will perform the final save after user edits.
         tasks[task_id]["status"] = "completed"
         tasks[task_id]["notes"] = final_markdown
-        tasks[task_id]["topics"] = raw_topics
-        tasks[task_id]["category"] = category
+        tasks[task_id]["topics"] = categories
+        tasks[task_id]["category"] = categories
         tasks[task_id]["keyPoints"] = key_points_list
         logger.info(f"✅ Task {task_id} completed successfully!")