Refactor invoice processing logic to remove legacy returned quantity fields and enhance data handling

- Updated invoice processing functions to eliminate legacy fields related to returned quantities, now relying on new balance movement and discharge records.
- Adjusted various components and services to reflect changes in quantity handling, including updates to the frontend for displaying used quantities instead of returned ones.
- Improved the logic for invoice total updates and validation processes to ensure consistency with the new data structure.

These changes aim to streamline invoice management and improve data integrity across the application.

frontend/src/lib/api/dashboard/a76/items.ts

@@ -52,7 +52,6 @@ export interface LineQuantities {
 
     // Special quantities
     quantity_temp_export?: number;
-    quantity_returned?: number;
 
     // Weight
     net_weight?: number;
@@ -338,8 +337,8 @@ export interface ImportLineWithBalance {
     unit_of_measure_code?: string;
     // Quantities
     quantity?: number;
-    quantity_returned_temp?: number;
-    quantity_returned?: number;
+    quantity_used_temp?: number;
+    quantity_used_def?: number;
     // Balance
     available_balance: number;
     has_balance: boolean;