Introduce db-migrator app for migrating flow-persistence, flow-quartz and data-index migrations

[mathecruz]

Summary

Adds db-migrator, a one-shot Job that runs Flyway migrations for the runtime, quartz, and data-index schema streams against a shared PostgreSQL database, then reports success/failure as JSON on the
container's termination message.

Depends on quarkus-flow-db-migration / quarkus-flow-db-migration-quartz from quarkiverse/quarkus-flow#1038, pinned to 2.0.0-SNAPSHOT until that PR is released.

Changes

• New db-migrator module (MigrationRunner, MigrationReport, StreamResult)
• Each stream runs on its own named Flyway datasource, so each gets an isolated history table on the shared schema
• Which streams to run is controlled by LOGIC_DB_MIGRATOR_INCLUDE