feat(backend): add /health endpoint

[tyler-dane]

Add /api/health endpoint to provide a health check with database connectivity verification.

---

  

[cursor]

Cursor Agent can help with this pull request. Just @cursor in comments and I'll start working on changes in this branch.
_{Learn more about Cursor Agents}

[tyler-dane]

@cursoragent fix existing broken tests and add new test to validate your new functionality

[cursor]

All tests are passing. Summary of added tests:

Summary

Added 8 tests for the health endpoint:

1. Basic functionality - Returns 200 OK with status "ok" and valid ISO timestamp
2. Timestamp validation - Ensures timestamp is recent (within 1 second of request time)
3. No authentication required - Endpoint is accessible without session
4. Invalid session handling - Works even with invalid session cookies
5. Database connectivity - Verifies database ping check works correctly
6. Response structure - Ensures consistent response format with exactly 2 fields
7. Concurrent requests - Handles multiple simultaneous requests (3 concurrent)
8. Content-type header - Verifies proper JSON content-type header

All tests are passing. The test suite covers:

• Basic endpoint functionality
• Response structure and validation
• Authentication/authorization (none required)
• Error handling and edge cases
• Performance (concurrent requests)
• HTTP headers

The implementation is tested and ready.

  

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}