feat: 實作 POS API 整合功能，包含商品與銷售訂單同步及韌性機制

app/Modules/Integration/Routes/api.php

@@ -0,0 +1,12 @@
+<?php
+
+use Illuminate\Support\Facades\Route;
+use App\Modules\Integration\Controllers\ProductSyncController;
+use App\Modules\Integration\Controllers\OrderSyncController;
+
+Route::prefix('api/v1/integration')
+    ->middleware(['api', 'integration.tenant', 'auth:sanctum']) // integration.tenant middleware to identify tenant
+    ->group(function () {
+        Route::post('products/upsert', [ProductSyncController::class, 'upsert']);
+        Route::post('orders', [OrderSyncController::class, 'store']);
+    });