Create batch video processing API endpoint

[clencyc]

Description

Allow users to queue multiple videos for processing/analysis in one request instead of doing them one-by-one.

Acceptance Criteria

• New endpoint: POST /api/batch/analyze
• Accepts array of video file IDs
• Returns batch_id for tracking progress
• Processes videos in parallel (max 3 concurrent)
• Webhook support: callback when batch completes
• Progress endpoint: GET /api/batch/{batch_id}/progress
• Result endpoint: GET /api/batch/{batch_id}/results
• Database schema updated for batch tracking
• Unit and integration tests

Implementation Details

• Request format:

  {
    "videos": ["video_id_1", "video_id_2"],
    "webhook_url": "https://example.com/callback",
    "priority": "normal"
  }

• Stores batch status in database/cache
• Uses Celery for async job management
• Returns job IDs for tracking

Files to Modify

• LiveEditBackend/app.py - add batch endpoints
• LiveEditBackend/tasks.py (create) - celery tasks
• Database migrations for batch table

Difficulty: Hard

Estimated time: 6-7 hours