feat: 修正庫存與撥補單邏輯並整合文件

1. 修復倉庫統計數據加總與樣式。
2. 修正可用庫存計算邏輯（排除不可銷售倉庫）。
3. 撥補單商品列表加入批號與效期顯示。
4. 修正撥補單儲存邏輯以支援精確批號轉移。
5. 整合 FEATURES.md 至 README.md。

app/Modules/Procurement/Models/PurchaseOrder.php

@@ -4,8 +4,7 @@ namespace App\Modules\Procurement\Models;
 
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
-use App\Modules\Inventory\Models\Warehouse;
-use App\Modules\Core\Models\User;
+
 
 class PurchaseOrder extends Model
 {
@@ -14,19 +13,19 @@ class PurchaseOrder extends Model
     use \Spatie\Activitylog\Traits\LogsActivity;
 
     protected $fillable = [
-        'po_number',
+        'code',
         'vendor_id',
         'warehouse_id',
         'user_id',
-        'order_date',
         'expected_delivery_date',
         'status',
         'total_amount',
-        'notes',
+        'tax_amount',
+        'grand_total',
+        'remark',
     ];
 
     protected $casts = [
-        'order_date' => 'date',
         'expected_delivery_date' => 'date',
         'total_amount' => 'decimal:2',
     ];
@@ -43,14 +42,13 @@ class PurchaseOrder extends Model
     {
         $snapshot = $activity->properties['snapshot'] ?? [];
         
-        $snapshot['po_number'] = $this->po_number;
+        $snapshot['po_number'] = $this->code;
         
         if ($this->vendor) {
             $snapshot['vendor_name'] = $this->vendor->name;
         }
-        if ($this->warehouse) {
-            $snapshot['warehouse_name'] = $this->warehouse->name;
-        }
+        // Warehouse relation removed in Strict Mode. Snapshot should be set via manual hydration if needed, 
+        // or during the procurement process where warehouse_id is known.
 
         $activity->properties = $activity->properties->merge([
             'snapshot' => $snapshot
@@ -62,15 +60,9 @@ class PurchaseOrder extends Model
         return $this->belongsTo(Vendor::class);
     }
 
-    public function warehouse(): \Illuminate\Database\Eloquent\Relations\BelongsTo
-    {
-        return $this->belongsTo(Warehouse::class);
-    }
 
-    public function user(): \Illuminate\Database\Eloquent\Relations\BelongsTo
-    {
-        return $this->belongsTo(User::class);
-    }
+
+
 
     public function items(): \Illuminate\Database\Eloquent\Relations\HasMany
     {