feat(workshop): restrict status flow, add mechanic notes, inventory part picker

- Service orders can no longer move backwards through the workshop pipeline.

- Added editable Reception / Diagnosis / Repair / Delivery notes in the detail modal.

- Added inventory-aware autocomplete when attaching parts to a service order.

pos/services/service_order_engine.py

@@ -13,7 +13,7 @@ VALID_TRANSITIONS = {
     'diagnosis': ['waiting_parts', 'repair', 'cancelled'],
     'waiting_parts': ['repair', 'cancelled'],
     'repair': ['quality_check', 'cancelled'],
-    'quality_check': ['ready', 'repair', 'cancelled'],
+    'quality_check': ['ready', 'cancelled'],
     'ready': ['delivered', 'cancelled'],
     'delivered': [],
     'cancelled': [],