docs: add Next.js Deno build troubleshooting

[avocet-bot]

Summary

• add Deno Deploy Next.js compatibility notes for ESM config, the known Next.js-on-Deno lint/type-check crash, and browser-only prerender failures
• update the Next.js tutorial with next.config.mjs guidance and build troubleshooting
• fix the tutorial text to refer to the "use client" directive

Validation

• deno fmt --check deploy/reference/frameworks.md examples/tutorials/next.md

[magurotuna]

Could we clarify the next/dynamic workaround for App Router here?

{ ssr: false } only works for Client Components. In Server Components, Next.js errors with ssr: false is not allowed with next/dynamic; the dynamic import needs to be moved into a Client Component wrapper.

As written, this can read as if users can apply dynamic(..., { ssr: false }) directly from any App Router page/server component, which may lead to a second build error while following the troubleshooting advice.

[magurotuna]

Looks good to me. The App Router next/dynamic / ssr: false caveat is now clear, and the focused docs checks pass locally.

[magurotuna]

We'll fix the build issue later