Add Cloudflare Workers deploy config via OpenNext

- Fix build:worker script to use opennextjs-cloudflare build
- Add open-next.config.ts required by OpenNext Cloudflare
- Update wrangler.toml main entry to .open-next/worker.js
- Ignore .open-next/ and .wrangler/ build artifacts

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

wrangler.toml

@@ -0,0 +1,8 @@
+name = "opennext-app"
+main = ".open-next/worker.js"
+compatibility_date = "2024-09-23"
+compatibility_flags = ["nodejs_compat"]
+
+[assets]
+directory = ".open-next/assets"
+binding = "ASSETS"