[+] Database system is now fully flexible: supports MySQL and SQLite (auto fallback)
[+] New config option: database.type (mysql/sqlite) in database.json
[+] Redis cache support: Set database.redis.enabled to true for Redis-based cache
[+] All SQL access is now routed through a DatabaseManager interface
[+] DefaultConfig and database.json now include all necessary options for MySQL, SQLite, and Redis
[+] Improved startup logging: shows active DB type, cache type (ExpiringMap/Redis) and connection status
[+] All cache and DB operations are now fully null-safe