Add missing Next.js middleware to wire up Supabase auth session handling

The updateSession helper existed in src/lib/supabase/middleware.ts but was
never connected to Next.js. Without this file, auth cookies were not refreshed
on navigation, causing authenticated users to be redirected back to the landing
page after login.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: felmonon

src/middleware.ts

@@ -0,0 +1,19 @@
+import { type NextRequest } from 'next/server';
+import { updateSession } from '@/lib/supabase/middleware';
+
+export async function middleware(request: NextRequest) {
+  return await updateSession(request);
+}
+
+export const config = {
+  matcher: [
+    /*
+     * Match all request paths except:
+     * - _next/static (static files)
+     * - _next/image (image optimization files)
+     * - favicon.ico (favicon file)
+     * - Public assets (svg, png, jpg, etc.)
+     */
+    '/((?!_next/static|_next/image|favicon\\.ico|.*\\.(?:svg|png|jpg|jpeg|gif|webp)$).*)',
+  ],
+};