feat: fully functional Admin Panel with 5-tab dashboard (closes #29)

[qiqi1616]

/claim #29

Summary

Replaces the placeholder AdminPanelPage with a fully functional 5-tab admin dashboard.

Backend (Express API)

• adminService.js — Full service layer: metrics, user management (list/detail/status), flagged job queue (approve/reject), dispute resolution (list/detail/resolve), platform controls
• adminController.js — 11 API endpoints wrapping service calls with error handling
• adminRoutes.js — Protected routes with server-side admin role guard (checks req.user.role === 'admin' on every request)

Frontend (Next.js)

• Admin Panel Page — 5-tab dashboard:
  • Metrics — Total users, jobs, open jobs, disputes, open disputes
  • Users — Table with role/status badges, searchable
  • Flagged — Job moderation queue with approve/reject actions
  • Disputes — Dispute queue with status tracking
  • Controls — Platform toggles (registration, job posting)

Acceptance Criteria

• Admin-only route guard (server-side role check)
• User management table with search/filter
• User status actions (suspend/reinstate/ban)
• Flagged job moderation queue
• Dispute resolution queue
• Platform controls
• Metrics dashboard
• Modular, independently testable sections

Closes #29

[BossChaos]

Code Review

PR: feat: fully functional Admin Panel with 5-tab dashboard (closes #29) by @qiqi1616

• 🔒 Admin panel — needs security review

Wallet: 0xdaE5d307339074A24F579dB48e7c639359D94904

Code review for SecureBananaLabs bug-bounty