feat: 優化操作紀錄顯示與邏輯 (恢復描述欄位、支援來源標記、改進快照)

app/Http/Controllers/InventoryController.php

@@ -103,7 +103,8 @@ class InventoryController extends Controller
         return \Illuminate\Support\Facades\DB::transaction(function () use ($validated, $warehouse) {
             foreach ($validated['items'] as $item) {
                 // 取得或建立庫存紀錄
-                $inventory = $warehouse->inventories()->firstOrCreate(
+                // 取得或初始化庫存紀錄
+                $inventory = $warehouse->inventories()->firstOrNew(
                     ['product_id' => $item['productId']],
                     ['quantity' => 0, 'safety_stock' => null]
                 );
@@ -111,8 +112,9 @@ class InventoryController extends Controller
                 $currentQty = $inventory->quantity;
                 $newQty = $currentQty + $item['quantity'];
 
-                // 更新庫存
-                $inventory->update(['quantity' => $newQty]);
+                // 更新庫存並儲存 (新紀錄: Created, 舊紀錄: Updated)
+                $inventory->quantity = $newQty;
+                $inventory->save();
 
                 // 寫入異動紀錄
                 $inventory->transactions()->create([