[David-Isaac-design]

Summary

Adds graceful shutdown handling for the background disbursement queue worker.

Closes #956

Changes

• Listen for tokio::signal::ctrl_c() in main.
• Signal the disbursement worker when shutdown is requested.
• Use tokio::select! in the worker loop to handle shutdown between processing cycles.
• Allow the currently active batch item to finish before the worker exits.
• Await the worker task before the application exits and database resources are released.

Validation

• git diff --check passes.
• Rust formatting, check, and tests could not be run because cargo is not available in the current environment.
• Only the files required for the worker shutdown flow were changed.

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@David-Isaac-design Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

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[ONEONUORA]

Great job @David-Isaac-design