[TODO Import][Client][Backlog] Admin problem management and review UI

[ferneediaz]

Imported from client/TODO.md.

Kanban

• Column: Backlog
• Area: Client

4.2 Problem Contribution & Admin

• Admin problem management page (/admin/problems):
  • List all problems with status (ACTIVE, DRAFT, REJECTED)
  • Search + filter by difficulty, status, tags
  • Create / Edit / Delete buttons
• Problem creation form (/admin/problems/new):
  • Fields: title, description (markdown editor), difficulty, tags, constraints, expected complexity, hints
  • Test cases editor: add/remove input/output pairs, toggle hidden
  • Starter code editors: one Monaco editor per language (tabs)
  • Editorial/solution editor (markdown + code)
  • Save as DRAFT or publish as ACTIVE
• Problem testing sandbox (/admin/problems/:id/test):
  • Full Monaco editor
  • Language selector
  • 'Run Tests' button → calls POST /api/problems/:id/execute
  • Shows test results (passed/failed per test case, output vs expected)
  • Ability to test with ALL test cases (including hidden)
  • Verify problem is solvable before publishing
• Community review queue (/admin/review):
  • List of problems in DRAFT status submitted by community
  • Review interface: see problem + test cases + starter code
  • 'Test in Sandbox' button
  • 'Approve' / 'Reject with reason' buttons
  • Contributor attribution
• Documentation page for contributors:
  • How to structure a problem folder
  • Required fields and format
  • Example problem folder structure
  • Link to /problems directory in repo
• Success Criteria: Admin can create, test, and publish problems; community problems can be reviewed ✅