feat(platform): Phase 5 — Human Review Queue
- Batch decisions: POST /reviews/batch-decision (up to 50 items)
- Parallel execution with allSettled, reports succeeded/failed counts
- Delegation: POST /reviews/:id/delegate
- Reassigns review with delegation metadata tracking
- Triggers notification to new assignee
- Auto-expiry: POST /reviews/expire
- Scans pending/assigned reviews past dueAt, marks expired
- Review stats: GET /reviews/stats
- Aggregates by status/priority/category, avg resolution time
- Computes pendingCount, overdueCount, avgResolutionHours
- New repo functions: listExpired, listAll
- 1,331 tests passing (7 new)