Add --watch mode for live re-scanning during skill development

[TheStack-ai]

Context

Currently pulser is run-once: edit SKILL.md → run pulser → see results → repeat. During active skill development, a --watch flag that re-runs on file changes would save time.

Proposed

pulser --watch
# Watches ~/.claude/skills/ for changes, re-runs scan on save

What to do

1. Add --watch flag to CLIOptions in src/types.ts
2. In src/index.ts, after initial scan, enter a watch loop using fs.watch (recursive) on the skills directory
3. Debounce re-scans (300ms) to avoid flooding on multi-file saves
4. Clear terminal and re-run the TUI monitor on each change

The TUI monitor (src/monitor/tui.ts) already handles terminal rewriting, so the rendering infrastructure exists.

Considerations

• fs.watch behavior varies across platforms — test on macOS and Linux
• Debounce is important: editors may trigger multiple events per save
• Ctrl+C should exit cleanly

Files to modify

• src/types.ts (CLIOptions)
• src/index.ts (watch loop)

Difficulty: Medium