feat: add dynamic sitemap.xml and robots.txt

sitemap.ts generates URLs for all static pages, stores, and coupons.
robots.ts allows all crawlers, blocks /api/, points to sitemap.

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

Author: ralyodio

apps/web/app/robots.ts

@@ -0,0 +1,8 @@
+import type { MetadataRoute } from 'next';
+
+export default function robots(): MetadataRoute.Robots {
+  return {
+    rules: { userAgent: '*', allow: '/', disallow: '/api/' },
+    sitemap: 'https://c0upons.com/sitemap.xml',
+  };
+}

apps/web/app/sitemap.ts

@@ -0,0 +1,39 @@
+import type { MetadataRoute } from 'next';
+import { getDb } from '@/lib/db';
+
+const BASE = 'https://c0upons.com';
+
+export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
+  const staticRoutes: MetadataRoute.Sitemap = [
+    { url: BASE, changeFrequency: 'daily', priority: 1 },
+    { url: `${BASE}/stores`, changeFrequency: 'daily', priority: 0.9 },
+    { url: `${BASE}/submit`, changeFrequency: 'monthly', priority: 0.7 },
+    { url: `${BASE}/docs`, changeFrequency: 'monthly', priority: 0.6 },
+    { url: `${BASE}/search`, changeFrequency: 'monthly', priority: 0.5 },
+  ];
+
+  try {
+    const db = getDb();
+
+    const stores = await db.sql`SELECT slug, created_at FROM stores ORDER BY created_at DESC`;
+    const coupons = await db.sql`SELECT id, created_at FROM coupons ORDER BY created_at DESC`;
+
+    const storeRoutes: MetadataRoute.Sitemap = stores.map((s: { slug: string; created_at: string }) => ({
+      url: `${BASE}/stores/${s.slug}`,
+      lastModified: s.created_at ? new Date(s.created_at) : undefined,
+      changeFrequency: 'weekly',
+      priority: 0.8,
+    }));
+
+    const couponRoutes: MetadataRoute.Sitemap = coupons.map((c: { id: number; created_at: string }) => ({
+      url: `${BASE}/coupons/${c.id}`,
+      lastModified: c.created_at ? new Date(c.created_at) : undefined,
+      changeFrequency: 'weekly',
+      priority: 0.6,
+    }));
+
+    return [...staticRoutes, ...storeRoutes, ...couponRoutes];
+  } catch {
+    return staticRoutes;
+  }
+}