Implement admin operations panel

[alexgduarte]

/claim #29

Summary

• Replaced the AdminPanelPage placeholder with a full admin operations console covering users, moderation, disputes, trust metrics, platform controls, and audit log.
• Added a web route guard for /admin; non-admin sessions are rewritten to a 403 page.
• Added server-side admin-role enforcement for every /api/admin/* route.
• Added admin API routes for paginated/filterable users, moderation queue, disputes, controls, metrics, and audit logs.
• Added mutation endpoints for user status changes, listing decisions, dispute rulings, and platform controls.
• Added append-only audit logging plus notification side effects for rejected listings and dispute rulings.
• Added focused API tests for non-admin denial, admin metrics/users, mutations, controls, and audit entries.

Validation

• node --check apps/api/src/services/adminService.js; node --check apps/api/src/controllers/adminController.js; node --check apps/api/src/routes/adminRoutes.js; node --check apps/api/src/tests/admin.test.js
• npm test
• npm run build -w apps/web
• git diff --cached --check

Notes

• The implementation stays within the repo's current mock-data architecture rather than introducing a database migration.
• The web admin surface uses seeded mock-service data for review, while the API enforces the real server-side admin JWT role check.
• I could not attach a short demo video because this local environment does not have ffmpeg or ImageMagick available.