Migrating Blocking Jobs to Async Handling

[maldwg]

As a developer,
I want to refactor the backend ednpoints to be asynchronous,
So that the API remains responsive.

Acceptance Criteria:

• Identify blocking endpoints (e.g., send-notifications).
• Make endpoints async
• Implement proper background task handling (using BackgroundTasks or a queue system like Celery if needed).
• Note: This is a larger refactor to be scheduled when performace requires it.