feat: 優化採購單操作紀錄與統一刪除確認 UI

- 優化採購單更新與刪除的活動紀錄邏輯 (PurchaseOrderController)
  - 整合更新異動為單一紀錄，包含品項差異
  - 刪除時記錄當下品項快照
- 統一採購單刪除確認介面，使用 AlertDialog 取代原生 confirm (PurchaseOrderActions)
- Refactor: 將 ActivityDetailDialog 移至 Components/ActivityLog 並優化樣式與大數據顯示
- 調整 UI 文字：將「總金額」統一為「小計」
- 其他模型與 Controller 的活動紀錄支援更新

app/Models/Product.php

@@ -80,11 +80,12 @@ class Product extends Model
     {
         $properties = $activity->properties;
         $attributes = $properties['attributes'] ?? [];
+        $snapshot = $properties['snapshot'] ?? [];
         
         // Handle Category Name Snapshot
         if (isset($attributes['category_id'])) {
             $category = Category::find($attributes['category_id']);
-            $attributes['category_name'] = $category ? $category->name : null;
+            $snapshot['category_name'] = $category ? $category->name : null;
         }
         
         // Handle Unit Name Snapshots
@@ -93,14 +94,15 @@ class Product extends Model
             if (isset($attributes[$field])) {
                 $unit = Unit::find($attributes[$field]);
                 $nameKey = str_replace('_id', '_name', $field);
-                $attributes[$nameKey] = $unit ? $unit->name : null;
+                $snapshot[$nameKey] = $unit ? $unit->name : null;
             }
         }
         
         // Always snapshot self name for context (so logs always show "Cola")
-        $attributes['name'] = $this->name;
+        $snapshot['name'] = $this->name;
 
         $properties['attributes'] = $attributes;
+        $properties['snapshot'] = $snapshot;
         $activity->properties = $properties;
     }