feat: add SQLite persistence and REST API for temporary whitelisting

- Migrate IP-based temporary whitelisting from file to SQLite storage
- Add REST API endpoints for managing temporary and permanent whitelists
- Create `.env.example` with required environment variables
- Document API endpoints in README.md and docs/api.md
- Add new dependency `modernc.org/sqlite` for SQLite support
- Update deployment and security documentation

config.go

@@ -19,7 +19,7 @@ func loadConfig() Config {
 		APIToken:        getEnv("AUTH_GATE_API_TOKEN", ""),
 		DataDir:         getEnv("DATA_DIR", "/data"),
 		CleanupInterval: parseDuration("CLEANUP_INTERVAL", 60*time.Second),
-		DBPath:          getEnv("AUTH_GATE_DB_PATH", "/data/auth-gate.db"),
+		DBPath:          getEnv("AUTH_GATE_DB_PATH", "./data/auth-gate.db"),
 	}
 }
 
@@ -38,4 +38,4 @@ func parseDuration(key string, defaultVal time.Duration) time.Duration {
 		}
 	}
 	return defaultVal
-}
+}