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/Middleware/TenantIdentificationMiddleware.php

@@ -0,0 +1,58 @@
+<?php
+
+namespace App\Modules\Integration\Middleware;
+
+use Closure;
+use Illuminate\Http\Request;
+use Stancl\Tenancy\Facades\Tenancy;
+use Symfony\Component\HttpFoundation\Response;
+
+class TenantIdentificationMiddleware
+{
+    /**
+     * Handle an incoming request.
+     *
+     * @param  \Closure(\Illuminate\Http\Request): (\Symfony\Component\HttpFoundation\Response)  $next
+     */
+    public function handle(Request $request, Closure $next): Response
+    {
+        // 1. Check for X-Tenant-Domain header
+        $domain = $request->header('X-Tenant-Domain');
+
+        if (! $domain) {
+            return response()->json([
+                'message' => 'Missing X-Tenant-Domain header.',
+            ], 400);
+        }
+
+        // 2. Find Tenant by domain
+        // Assuming domains are stored in 'domains' table and linked to tenants
+        // Or using Stancl's tenant finder. 
+        // Stancl Tenancy usually finds by domain automatically for web routes, but for API 
+        // we are doing manual identification because we might not be using subdomains for API calls (or maybe we are).
+        // If the API endpoint is centrally hosted (e.g. api.star-erp.com/v1/...), we need this header.
+        
+        // Let's try to initialize tenancy manually.
+        // We need to find the tenant model that has this domain.
+        try {
+             $tenant = \App\Modules\Core\Models\Tenant::whereHas('domains', function ($query) use ($domain) {
+                 $query->where('domain', $domain);
+             })->first();
+
+             if (! $tenant) {
+                 return response()->json([
+                     'message' => 'Tenant not found.',
+                 ], 404);
+             }
+
+             Tenancy::initialize($tenant);
+
+        } catch (\Exception $e) {
+            return response()->json([
+                'message' => 'Tenant initialization failed: ' . $e->getMessage(),
+            ], 500);
+        }
+
+        return $next($request);
+    }
+}