[REFACTOR] 實作側邊欄與儀表板多語系化，修復 UI 位移與樣式優化

app/Http/Middleware/SetLocale.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace App\Http\Middleware;
+
+use Closure;
+use Illuminate\Http\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+class SetLocale
+{
+    /**
+     * Handle an incoming request.
+     *
+     * @param  \Closure(\Illuminate\Http\Request): (\Symfony\Component\HttpFoundation\Response)  $next
+     */
+    public function handle(Request $request, Closure $next): Response
+    {
+        if (session()->has('locale')) {
+            $locale = session()->get('locale');
+            if (in_array($locale, ['zh_TW', 'en', 'ja'])) {
+                app()->setLocale($locale);
+            }
+        }
+
+        return $next($request);
+    }
+}