feat: add devaluation support to stock movements

- Add 'devaluation' to stock movement types
- Add validation to ensure trackable items for devaluation
- Improve error handling for devaluation operations

app/models/stock_movement.py

@@ -13,7 +13,7 @@ class StockMovement(db.Model):
     id = db.Column(db.Integer, primary_key=True)
     movement_type = db.Column(
         db.String(20), nullable=False, index=True
-    )  # 'adjustment', 'transfer', 'sale', 'rent', 'purchase', 'return', 'waste'
+    )  # 'adjustment', 'transfer', 'sale', 'rent', 'purchase', 'return', 'waste', 'devaluation'
     stock_item_id = db.Column(db.Integer, db.ForeignKey("stock_items.id"), nullable=False, index=True)
     warehouse_id = db.Column(db.Integer, db.ForeignKey("warehouses.id"), nullable=False, index=True)
     quantity = db.Column(db.Numeric(10, 2), nullable=False)  # Positive for additions, negative for removals

app/routes/inventory.py

@@ -983,6 +983,9 @@ def new_movement():
 
                 # Process devaluation if enabled
                 if devalue_enabled:
+                    if not item.is_trackable:
+                        raise ValueError(_("Stock item is not trackable. Devaluation requires trackable items."))
+                    
                     base_cost = item.default_cost or Decimal("0")
                     if base_cost <= 0:
                         raise ValueError(_("Stock item must have a default cost to perform devaluation"))