Simplify policy system design based on feedback

Key changes:
- Restructure taxonomy: detection modes (trigger/safety, set, pair) + action types (prompt, command)
- Add required `name` field for human-friendly promise tag display (e.g., "✓ Source/Test Pairing")
- Remove priority and defer features (not needed yet)
- Clarify .deepwork/tmp is gitignored, so cleanup is not critical
- Shorten output format - group by policy name, use simple arrow notation for correspondence
- Update all examples to include name field

Author: claude