fix: mark sitemap as dynamic to avoid DB query at build time

The sitemap queries the database, which is only reachable at runtime
(not during next build where the 'db' hostname is unavailable).

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

app/sitemap.ts

@@ -1,4 +1,7 @@
 import type { MetadataRoute } from 'next'
+
+export const dynamic = 'force-dynamic'
+
 import { db } from '@/lib/db'
 import { tournaments, teams, goals } from '@/lib/db/schema'
 import { asc } from 'drizzle-orm'