fix(GRO-636): input validation fixes for 5 API routes

Adds Zod validation across 5 API routes:

1. invoices GET / — query param validation (uuid, enum, int bounds)
2. book POST / — future-time refinement on startTime
3. appointments — recurrence series capped at 1 year
4. services — durationMinutes capped at 480 (8 hours)
5. stripe-webhooks — UUID validation on invoice IDs before DB lookup

Closes GRO-636

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/routes/services.ts

@@ -9,7 +9,7 @@ const createServiceSchema = z.object({
   name: z.string().min(1).max(200),
   description: z.string().max(2000).optional(),
   basePriceCents: z.number().int().positive(),
-  durationMinutes: z.number().int().positive(),
+  durationMinutes: z.number().int().positive().max(480),
   active: z.boolean().default(true),
 });