watch mode for real-time video monitoring

[jdwit]

Add a ytstudio videos watch VIDEO_ID command that polls video stats at a configurable interval and displays changes in real-time.

Use case: After publishing a video, creators want to monitor performance without refreshing YouTube Studio.

Proposed behavior:

• ytstudio videos watch VIDEO_ID — polls every 60s (default)
• ytstudio videos watch VIDEO_ID --interval 30 — custom interval
• Shows: views, likes, comments delta since start and since last poll
• Optional: --alert-comments to highlight new comments inline
• Exit with Ctrl+C, prints summary

Output:

Watching: De Coalitie (vSzx36FRX-E)
[14:30:00] 42,400 views (+0)  1,563 likes (+0)  127 comments (+0)
[14:31:00] 42,412 views (+12) 1,564 likes (+1)  127 comments (+0)

Why: Useful for launch day monitoring and for automation (pipe to alerting).