feat: Added Comments CRUD Feature

[Aditi10909]

Task Comments Module

Backend

• RESTful API endpoints for comments (CRUD) linked to tasks and accounts:
  • POST /accounts/{account_id}/tasks/{task_id}/comments
  • GET /accounts/{account_id}/tasks/{task_id}/comments
  • PUT /accounts/{account_id}/tasks/{task_id}/comments/{comment_id}
  • DELETE /accounts/{account_id}/tasks/{task_id}/comments/{comment_id}
• Validations: text input, authentication, and account/task isolation.
• Tests:
  • Automated: API and service-level tests for create, read, update, delete, input validation, auth, and isolation.
  • Manual: verified persistence, update timestamps, malformed requests, and deletion.

Frontend

• React UI for managing task comments:
  • Components: CommentsList, CommentForm, CommentItem
  • Features: view, add, edit, delete comments