Remove deprecated middleware and update component tests for branding and auth enhancements

- Deleted `middleware.disabled.ts` as it is no longer needed.
- Refactored `HeroSection` and `HomePage` tests to align with updated branding and messaging.
- Modified `DemoCredentialsModal` to support auto-filled demo credentials in login links.
- Mocked `ThemeToggle`, `LocaleSwitcher`, and `DemoCredentialsModal` in relevant tests.
- Updated admin tests to use `QueryClientProvider` and refactored API mocks for `AdminPage`.
- Replaced test assertions for stats section and badges with new branding content.

frontend/src/middleware.disabled.ts

@@ -1,39 +0,0 @@
-import { NextResponse } from 'next/server';
-import type { NextRequest } from 'next/server';
-import createMiddleware from 'next-intl/middleware';
-import { routing } from './lib/i18n/routing';
-
-// Create next-intl middleware for locale handling
-const intlMiddleware = createMiddleware(routing);
-
-export function middleware(request: NextRequest) {
-  const { pathname } = request.nextUrl;
-
-  // Block access to /dev routes in production (handles both /dev and /[locale]/dev)
-  // Match: /dev, /en/dev, /it/dev, etc.
-  if (pathname === '/dev' || pathname.match(/^\/[a-z]{2}\/dev($|\/)/)) {
-    const isProduction = process.env.NODE_ENV === 'production';
-
-    if (isProduction) {
-      // Return 404 in production
-      return new NextResponse(null, { status: 404 });
-    }
-  }
-
-  // Handle locale routing with next-intl
-  return intlMiddleware(request);
-}
-
-export const config = {
-  // Match all pathnames except for:
-  // - API routes (/api/*)
-  // - Static files (/_next/*, /favicon.ico, etc.)
-  // - Files in public folder (images, fonts, etc.)
-  matcher: [
-    // Match all pathnames except for
-    '/((?!api|_next|_vercel|.*\\..*).*)',
-    // However, match all pathnames within /api/
-    // that don't end with a file extension
-    '/api/(.*)',
-  ],
-};