CLI retry command to re-run a failed video

[alimaandev]

Problem

The desktop app can retry a failed video (AppController.queue_retry), but the CLI has no equivalent — a failed generate means starting over.

Task

Add python -m shortube.main retry <video_id> that resets the video to pending and re-runs the pipeline, reusing the resume logic in shortube/pipeline.py (cached script/storyboard/voiceover are reused).

Acceptance criteria

• retry resets status and re-runs the pipeline for the given id
• Unknown id prints a clear error and exits non-zero
• --dry-run supported
• Unit test in tests/ with run_pipeline mocked

Files

• shortube/main.py
• shortube/pipeline.py (read-only reference)