Daily rewards:
- Server now tracks streak, prevents double-claim, resets on missed day
- GET endpoint returns current state (streak, claimed status, today's reward)
- Updates profile daily_streak + last_daily_reward columns
- Frontend fetches state from server instead of relying on local store

Achievements:
- New scene with category filters, progress bars, tier badges
- POST check action recalculates all progress from player stats
- game.php now tracks win_streak and checks achievements on game end
- Rewards (coins/XP) auto-granted when achievement completes

Challenges:
- Claim tracking via economy_transactions prevents double-claims
- Fixed column name (reason, not description)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>