refactor: move transaction management from services to API endpoints

- Services now use db.flush() instead of db.commit() for database operations
- API endpoints handle transaction commit after service calls
- Remove db.rollback() from services (let exception handlers manage this)
- Ensures consistent transaction boundaries at API layer

This pattern gives API endpoints full control over when to commit,
allowing for better error handling and potential multi-operation transactions.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/api/v1/vendor/inventory.py

@@ -36,7 +36,9 @@ def set_inventory(
     db: Session = Depends(get_db),
 ):
     """Set exact inventory quantity (replaces existing)."""
-    return inventory_service.set_inventory(db, current_user.token_vendor_id, inventory)
+    result = inventory_service.set_inventory(db, current_user.token_vendor_id, inventory)
+    db.commit()
+    return result
 
 
 @router.post("/inventory/adjust", response_model=InventoryResponse)
@@ -46,7 +48,9 @@ def adjust_inventory(
     db: Session = Depends(get_db),
 ):
     """Adjust inventory (positive to add, negative to remove)."""
-    return inventory_service.adjust_inventory(db, current_user.token_vendor_id, adjustment)
+    result = inventory_service.adjust_inventory(db, current_user.token_vendor_id, adjustment)
+    db.commit()
+    return result
 
 
 @router.post("/inventory/reserve", response_model=InventoryResponse)
@@ -56,7 +60,9 @@ def reserve_inventory(
     db: Session = Depends(get_db),
 ):
     """Reserve inventory for an order."""
-    return inventory_service.reserve_inventory(db, current_user.token_vendor_id, reservation)
+    result = inventory_service.reserve_inventory(db, current_user.token_vendor_id, reservation)
+    db.commit()
+    return result
 
 
 @router.post("/inventory/release", response_model=InventoryResponse)
@@ -66,7 +72,9 @@ def release_reservation(
     db: Session = Depends(get_db),
 ):
     """Release reserved inventory (cancel order)."""
-    return inventory_service.release_reservation(db, current_user.token_vendor_id, reservation)
+    result = inventory_service.release_reservation(db, current_user.token_vendor_id, reservation)
+    db.commit()
+    return result
 
 
 @router.post("/inventory/fulfill", response_model=InventoryResponse)
@@ -76,7 +84,9 @@ def fulfill_reservation(
     db: Session = Depends(get_db),
 ):
     """Fulfill reservation (complete order, remove from stock)."""
-    return inventory_service.fulfill_reservation(db, current_user.token_vendor_id, reservation)
+    result = inventory_service.fulfill_reservation(db, current_user.token_vendor_id, reservation)
+    db.commit()
+    return result
 
 
 @router.get("/inventory/product/{product_id}", response_model=ProductInventorySummary)
@@ -119,9 +129,11 @@ def update_inventory(
     db: Session = Depends(get_db),
 ):
     """Update inventory entry."""
-    return inventory_service.update_inventory(
+    result = inventory_service.update_inventory(
         db, current_user.token_vendor_id, inventory_id, inventory_update
     )
+    db.commit()
+    return result
 
 
 @router.delete("/inventory/{inventory_id}", response_model=InventoryMessageResponse)
@@ -132,4 +144,5 @@ def delete_inventory(
 ):
     """Delete inventory entry."""
     inventory_service.delete_inventory(db, current_user.token_vendor_id, inventory_id)
+    db.commit()
     return InventoryMessageResponse(message="Inventory deleted successfully")