Security:
- Remove hardcoded password fallbacks from application-druid.yml
- Add table name whitelist validation to SysFaultService & SysAlarmService
- Externalize VehicleSyncTask webhook URL to IotProperties config

Concurrency & Resource Management:
- Fix AbstractMqttConsumer reconnect/disconnect race (synchronized)
- Fix MqttClient resource leaks in disconnect() with separate try blocks
- Fix AbstractDynamicMqttConsumer broken-state MqttClient reuse
- Fix TDengineService stableColumnCache unbounded growth (MAX_CACHE_SIZE=1000)

Input Validation:
- Add null/empty checks to MqttGenericConsumer (controllerId, path, timestamp)
- Add null/empty checks to MqttFaultConsumer (controllerId, deviceId, type, desc)
- Guard against ArrayIndexOutOfBoundsException on topic path split

Tests:
- Update VehicleSyncTaskTest for new IotProperties constructor param
- All 79 tests pass, build succeeds