- Add price_min/price_max filters per keyword (stored in cents)
- Add allowed_postcodes filter per keyword (text[] array)
- Add mute hours per user with cross-midnight support
- Add digest mode with configurable interval and buffered summaries
- 10 new bot commands: /price_min, /price_max, /clear_price, /postcode,
/clear_postcode, /mute_hours, /mute_off, /digest_on, /digest_off, /status
- Updated keyword card display to show price range and postcodes
- New migrations: 05-keyword-filters.sql, 06-user-settings.sql