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/Inventory/Models/Warehouse.php

@@ -4,7 +4,7 @@ namespace App\Modules\Inventory\Models;
 
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
-use App\Modules\Procurement\Models\PurchaseOrder; // Cross-module dependency (Procurement)
+
 
 class Warehouse extends Model
 {
@@ -17,6 +17,11 @@ class Warehouse extends Model
         'name',
         'address',
         'description',
+        'is_sellable',
+    ];
+
+    protected $casts = [
+        'is_sellable' => 'boolean',
     ];
 
     public function getActivitylogOptions(): \Spatie\Activitylog\LogOptions
@@ -43,10 +48,7 @@ class Warehouse extends Model
         return $this->hasMany(Inventory::class);
     }
 
-    public function purchaseOrders(): \Illuminate\Database\Eloquent\Relations\HasMany
-    {
-        return $this->hasMany(PurchaseOrder::class);
-    }
+
 
     public function products(): \Illuminate\Database\Eloquent\Relations\BelongsToMany
     {