feat(web): import oh-my-openagent-web Next.js + Cloudflare Workers site

Imports the public marketing site previously living in
../oh-my-opencode-web. Independent of the npm plugin: own package.json,
bun.lock, tsconfig.json. Not included in the published package — root
files: array still only ships dist/, bin/, postinstall.mjs.

Stack:
- Next.js 15.5 App Router + RSC, deployed to Cloudflare Workers via
  @opennextjs/cloudflare (build target .open-next/worker.js).
- Tailwind v4 + shadcn/ui primitives.
- next-intl with 4 locales (en/ja/ko/zh) under app/[locale]/.
- Playwright e2e tests under web/e2e/.
- Custom domains ohmyopenagent.com (primary) and ohmyopencode.org
  (legacy alias) declared in web/wrangler.toml.

Source files were re-formatted via `bun run format` to bring them in
line with the existing .prettierrc (singleQuote: false). Functional code
unchanged.

web/app/robots.ts

@@ -0,0 +1,11 @@
+import type { MetadataRoute } from "next"
+
+export default function robots(): MetadataRoute.Robots {
+  return {
+    rules: {
+      userAgent: "*",
+      allow: "/",
+    },
+    sitemap: "https://ohmyopenagent.com/sitemap.xml",
+  }
+}