docs: update README for 4-category consent system
- Add achievements and server-status to sync command list
- Mention config screen as alternative to commands for consent toggles
- Update roadmap checkbox to reflect all 4 consent categories
- Remove completed items from Future Possibilities
- Add PlayerSyncPreferencesStore to project structure
- Update architecture diagram with consent store and new storage
- Add sync-preferences/ to configuration files section
- Remove RateLimiter from architecture (server-side login removed)