Fixed 404 error added PATCH/assign and implement validation

[gujju7bhai]

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[gujju7bhai]

Summary

• Added comprehensive integration tests using Jest and Supertest, strictly covering success paths, validation failures, and 404 edge cases.

• Fixed critical routing and logic bugs: resolved the PUT /tasks/:id 404 issue (params destructuring), corrected DELETE array index evaluation, and fixed substring status matching in getByStatus.

• Implemented the PATCH /tasks/:id/assign endpoint, extracting validation logic into a dedicated utils/validators.js file for cleaner architecture.

• Included detailed bug reports and submission notes addressing architectural observations (e.g., Jest open handles and app.listen separation).

Test plan

• npm install && npm test (Executes the full Jest test suite to verify bug fixes and the new endpoint).

• Review the bug report and submission notes for detailed breakdowns of the fixes and future architectural recommendations.

• Manually verify PATCH /tasks/:id/assign via Postman: test a valid string, an empty string {"assignee": " "}, and a non-existent task ID.

• Manually verify PUT /tasks/:id successfully updates an existing task instead of throwing a 404 Not Found error.