add user ownership to created tasks

[ranuru]

This pull request adds full support for editing and deleting challenges, improves challenge listing and detail displays, and strengthens backend security and data handling. The most important changes include adding an Edit Challenge page and route, showing author information, enabling challenge deletion, and updating backend APIs to support these features and enforce authentication.

Frontend: Challenge Editing, Deletion, and Display Improvements

• Added a new EditChallengePage with full form functionality for editing challenge details, schemas, and test cases. The page is accessible via a new protected route (/challenges/:id/edit). [1] [2] [3]
• On the challenge detail page (ChallengePage.jsx), added "Edit" and "Delete" actions, visible only to the challenge author or admins. Deleting a challenge now navigates back to the challenge list. [1] [2] [3]
• Challenge list and detail pages now display the author (createdBy) of each challenge. [1] [2] [3]
• Added NavBar to the challenge list page for consistent navigation.

Backend: API Enhancements and Security

• The ChallengeController now sets the createdBy field when creating challenges and exposes it in challenge listings. [1] [2]
• Refactored challenge creation logic to use helper methods for schemas and test cases, improving maintainability.
• Updated security configuration to require authentication for editing (PUT) and deleting (DELETE) challenges.
• The development user now has the ADMIN role for easier testing of admin features.

Other

• Minor backend code cleanup: removed unnecessary comments and improved imports. [1] [2]