feat: specsmith watch — live governance daemon

[tbitcs]

Problem

Governance drift happens gradually — code changes without ledger updates, new files without REQ coverage, CI modifications without tool registry alignment. Currently you have to manually run \specsmith audit\ to catch drift.

Proposed Solution

\specsmith watch --project-dir .\ runs a background daemon that:

1. Watches for file changes via filesystem events
2. Auto-validates governance consistency in real-time
3. Alerts when LEDGER.md hasn't been updated after code changes
4. Alerts when REQ↔TEST coverage drops below threshold
5. Alerts when CI config diverges from tool registry
6. Provides pre-commit hook integration (beyond just lint)
7. WebSocket feed for the React dashboard
8. Desktop notifications (optional)

Use Cases

• Developer makes code changes → daemon alerts 'LEDGER.md not updated'
• Someone edits CI manually → daemon alerts 'CI no longer matches tool registry'
• New test file added → daemon suggests 'add Covers: REQ-xxx reference'

[tbitcs]

Implemented as specsmith watch command with polling loop (optional watchdog for faster detection). Alerts on: LEDGER.md not updated after code changes, governance drift. Cross-platform (Windows/Linux/macOS). Ctrl+C to stop. Closes #16.