Performance optimizations: Bundle size reduction

Optimizations implemented:
1. Font display: swap + preload for critical fonts
2. ReactQueryDevtools: Lazy load in dev only, exclude from production
3. Auth forms code splitting: LoginForm, PasswordResetRequestForm
4. Remove invalid swcMinify option (default in Next.js 15)

Results:
- Login page: 178 kB → 104 kB (74 kB saved, 42% reduction)
- Password reset: 178 kB → 104 kB (74 kB saved, 42% reduction)
- Homepage: 108 kB (baseline 102 kB shared + 6 kB page)

Remaining issue:
- 102 kB baseline shared by all pages (React Query + Auth loaded globally)

frontend/src/app/providers.tsx

@@ -1,11 +1,20 @@
 'use client';
 
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
-import { ReactQueryDevtools } from '@tanstack/react-query-devtools';
-import { useState } from 'react';
+import { lazy, Suspense, useState } from 'react';
 import { ThemeProvider } from '@/components/theme';
 import { AuthInitializer } from '@/components/auth';
 
+// Lazy load devtools - only in development, never in production
+const ReactQueryDevtools =
+  process.env.NODE_ENV === 'development'
+    ? lazy(() =>
+        import('@tanstack/react-query-devtools').then((mod) => ({
+          default: mod.ReactQueryDevtools,
+        }))
+      )
+    : null;
+
 export function Providers({ children }: { children: React.ReactNode }) {
   const [queryClient] = useState(
     () =>
@@ -29,7 +38,11 @@ export function Providers({ children }: { children: React.ReactNode }) {
       <QueryClientProvider client={queryClient}>
         <AuthInitializer />
         {children}
-        <ReactQueryDevtools initialIsOpen={false} />
+        {ReactQueryDevtools && (
+          <Suspense fallback={null}>
+            <ReactQueryDevtools initialIsOpen={false} />
+          </Suspense>
+        )}
       </QueryClientProvider>
     </ThemeProvider>
   );