auto-claude: subtask-1-2 - Update middleware.ts to add authentication protect

- Add server-side authentication check for /[locale]/dashboard routes
- Create Supabase client in middleware to verify user session
- Redirect unauthenticated users to /[locale]/login with locale preservation
- Chain to existing i18n middleware for all other routes
- Authentication check runs before i18n middleware processing

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/middleware.ts

@@ -1,12 +1,45 @@
-import createMiddleware from 'next-intl/middleware';
+import createIntlMiddleware from 'next-intl/middleware';
+import { NextRequest, NextResponse } from 'next/server';
 import { locales, defaultLocale } from './i18n/config';
+import { createClient } from '@/lib/supabase/middleware';
 
-export default createMiddleware({
+const intlMiddleware = createIntlMiddleware({
   locales,
   defaultLocale,
   localePrefix: 'always',
 });
 
+export async function middleware(request: NextRequest) {
+  // Create a response object to pass to Supabase client
+  let response = NextResponse.next({
+    request: {
+      headers: request.headers,
+    },
+  });
+
+  // Check if accessing dashboard route
+  const pathname = request.nextUrl.pathname;
+  const isDashboardRoute = pathname.match(/^\/(de|en|sr)\/dashboard/);
+
+  if (isDashboardRoute) {
+    // Create Supabase client
+    const supabase = createClient(request, response);
+
+    // Check authentication
+    const { data: { user } } = await supabase.auth.getUser();
+
+    if (!user) {
+      // Extract locale from path
+      const locale = pathname.split('/')[1];
+      // Redirect to login page with locale preserved
+      return NextResponse.redirect(new URL(`/${locale}/login`, request.url));
+    }
+  }
+
+  // Continue with i18n middleware for all routes
+  return intlMiddleware(request);
+}
+
 export const config = {
   matcher: [
     '/',