YouTube Timestamp Modal

About

#Summary
A Chrome extension for organizing YouTube timestamps with a floating modal, manual entries, and comment-based extraction.

#Detailed description
`YouTube Timestamp Modal` adds a dedicated timestamp modal to YouTube watch pages so you can quickly capture, review, and jump to important moments.

Key features:

- Manual timestamp entry (`ss / m:ss / h:mm:ss`)
- Click-to-seek behavior
- Timestamp extraction from comments (via server API)
- Include replies toggle
- Duplicate timestamp removal toggle
- Manual entry manager page (grouped by video, edit/delete)
- Copy timestamped YouTube URLs
- Action popup menu (feature on/off, manual list link, external links)

Data handling:

- Settings and manual entries are stored in `chrome.storage.local`.
- Comment extraction results are cached per video with TTL-based refresh.