[BE-89] Graceful shutdown and Bull queue drain

[yusuftomilola]

Overview

main.ts does not enable shutdown hooks. On deploy or restart, in-flight HTTP requests and running Bull jobs are killed mid-execution, which can leave payments and invoices half-processed.

Tasks

• Call app.enableShutdownHooks() and handle SIGTERM/SIGINT.
• Stop accepting new connections, then wait for in-flight requests up to a configurable timeout.
• Implement OnModuleDestroy in queue-consuming modules to let active jobs finish and close the Bull connection cleanly.
• Close the TypeORM connection and Redis clients explicitly.
• Log each shutdown phase so a stuck shutdown is diagnosable.

Acceptance Criteria

• Sending SIGTERM during an active request completes that request before exit.
• An in-progress Bull job either finishes or is returned to the queue — never silently lost.
• The process exits within the configured timeout rather than hanging.

Notes for Contributors

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