Refactor production and stock tests to remove UOM dependency

- Updated production.spec.ts, stock-adjustments.spec.ts, and stock-transfers.spec.ts to eliminate UOM references in API seeder and test cases.
- Adjusted ApiSeeder methods to remove UOM parameters from stock receiving and production template creation.
- Revised documentation to reflect changes in UOM handling, emphasizing that stock is counted in base UOM only.
- Introduced new enums for MeasureUnit and StageQtyUnit to clarify content size and stage input quantities.
- Implemented ItemContent service to validate and normalize content sizes.
- Updated smoke tests to validate production stage inputs expressed in content units, ensuring correct consumption calculations.
- Modified frontend UOM label handling to reflect the removal of per-line UOMs in document lines.

Backend/ERPCore/Controllers/ItemsController.cs

@@ -81,11 +81,4 @@ public sealed class ItemsController : ApiControllerBase
     [ProducesResponseType(StatusCodes.Status404NotFound)]
     public async Task<ActionResult<ItemReorderSettingsDto>> UpdateReorder(int itemId, [FromBody] UpdateReorderRequest request, CancellationToken ct)
         => Ok(await _items.UpdateReorderAsync(itemId, request, ct));
-
-    /// <summary>Replace the item's UOM conversions (FR-MD-02).</summary>
-    [HttpPut("{itemId:int}/uom-conversions")]
-    [ProducesResponseType(typeof(ItemUomConversionsDto), StatusCodes.Status200OK)]
-    [ProducesResponseType(StatusCodes.Status404NotFound)]
-    public async Task<ActionResult<ItemUomConversionsDto>> UpdateUomConversions(int itemId, [FromBody] UpdateUomConversionsRequest request, CancellationToken ct)
-        => Ok(await _items.UpdateUomConversionsAsync(itemId, request, ct));
 }