feat: add middleware to redirect www and railway.app to canonical domain

301 redirects for:
- www.c0upons.com → https://c0upons.com
- *.railway.app / *.up.railway.app → https://c0upons.com
- http → https

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

Author: ralyodio

apps/web/middleware.ts

@@ -0,0 +1,31 @@
+import { NextRequest, NextResponse } from 'next/server';
+
+const CANONICAL = 'https://c0upons.com';
+
+export function middleware(req: NextRequest) {
+  const host = req.headers.get('host') ?? '';
+  const proto = req.headers.get('x-forwarded-proto') ?? 'https';
+
+  // Strip www
+  const isWww = host.startsWith('www.');
+  // Redirect railway temp domain to canonical
+  const isRailway = host.endsWith('.railway.app') || host.endsWith('.up.railway.app');
+  // Redirect plain http to https (in case Railway forwards it)
+  const isHttp = proto === 'http';
+
+  if (isWww || isRailway || isHttp) {
+    const url = req.nextUrl.clone();
+    url.protocol = 'https';
+    url.host = 'c0upons.com';
+    url.port = '';
+    return NextResponse.redirect(url, { status: 301 });
+  }
+
+  return NextResponse.next();
+}
+
+export const config = {
+  matcher: [
+    '/((?!_next/static|_next/image|favicon\\.svg|favicon\\.ico|.*\\.png|.*\\.svg|.*\\.jpg|.*\\.webp).*)',
+  ],
+};