ADD: Warehouse inventory management system

- Add WarehouseItem model with bilingual names (FA/EN) and bilingual counting units
- Add WarehouseItemTransaction model for IN/OUT movements with reason and actor
- Add WarehouseItemStock model for denormalized per-(item×warehouse) running balance
- Add warehouseItemService with full CRUD, atomic stock updates via $inc, negative stock guard, and aggregation queries for per-item/per-warehouse/total stock
- Add warehouseItemController and REST routes at /api/warehouse-items
- Add warehouseService, warehouseController, warehouseRoutes for warehouse location CRUD at /api/warehouses
- Register both route groups in routerEndpoints.js

components/warehouse/warehouseModel.js

@@ -0,0 +1,34 @@
+const mongoose = require('mongoose')
+const ObjectID = mongoose.Schema.Types.ObjectId
+
+const warehouseSchema = new mongoose.Schema(
+    {
+        name: {
+            type: String,
+            required: true,
+        },
+        code: {
+            type: String,
+            unique: true,
+        },
+        location: {
+            address: String,
+            coordinates: [Number], // [long, lat]
+        },
+        manager: {
+            type: ObjectID,
+            ref: 'User',
+        },
+        description: String,
+        isActive: {
+            type: Boolean,
+            default: true,
+        },
+    },
+    {
+        timestamps: true,
+    }
+)
+
+const Warehouse = mongoose.model('Warehouse', warehouseSchema)
+module.exports = Warehouse