feat(backend): implement v2 domain slice and live smoke

backend/command-api/src/contracts/commands/staff-review.js

@@ -0,0 +1,11 @@
+import { z } from 'zod';
+
+export const staffReviewSchema = z.object({
+  tenantId: z.string().uuid(),
+  businessId: z.string().uuid(),
+  staffId: z.string().uuid(),
+  assignmentId: z.string().uuid(),
+  rating: z.number().int().min(1).max(5),
+  reviewText: z.string().max(5000).optional(),
+  tags: z.array(z.string().min(1).max(80)).max(20).optional(),
+});