Add /api/dashboard/stats route that provides admin dashboard statistics:
- Total counts (games, benchmarks, users)
- Pending moderation items (reports, suggestions)
- 30-day activity metrics (recent benchmarks, recent games)
- Top 10 contributors by entry count
- Sync health breakdown by status
- Games by source distribution
- Playability distribution
Auth: requireContributorOrAdmin guard
Route registered in lib/api/index.ts
adrianbonpin