refactor: alternative healthcheck

[matiwinnetou]

  Individual Health Indicators (automatically aggregated by Spring Boot Actuator):
  - DatabaseHealthIndicator - Database connectivity via parameters loading
  - ParametersHealthIndicator - Parameters configuration loading
  - ParametersRefInputHealthIndicator - Parameters reference input loading
  - WalletHealthIndicator - Wallet UTXO availability
  - StakingHealthIndicator - FLDT staking status
  - SyncHealthIndicator - Blockchain sync status

  Endpoints Available:
  - /actuator/health - Aggregated health status with detailed component breakdown
  - /__internal__/healthcheck - Legacy endpoint (unchanged for backward compatibility)

  The /actuator/health endpoint will show something like:
  {
    "status": "UP",
    "components": {
      "database": { "status": "UP", "details": {...} },
      "parameters": { "status": "UP", "details": {...} },
      "parametersRefInput": { "status": "UP", "details": {...} },
      "wallet": { "status": "DOWN", "details": {...} },
      "staking": { "status": "DOWN", "details": {...} },
      "sync": { "status": "UP", "details": {...} }
    }
  }

  This gives you both granular monitoring and maintains existing integrations.