docs: add One framework to code examples

[natew]

Summary

• Adds One framework tab to all framework code groups across install, queries, mutators, and server-zql docs
• One uses file-based API routes (+api.ts files) with standard Request/Response, so the integration is clean and minimal
• Also updates prose mentions to include One alongside TanStack Start and Next.js

Files changed

• contents/docs/install.mdx - query + mutate endpoint examples
• contents/docs/queries.mdx - query endpoint example
• contents/docs/mutators.mdx - mutate endpoint + error handling + async tasks examples
• contents/docs/server-zql.mdx - SSR section

[vercel]

@natew is attempting to deploy a commit to the Rocicorp Team on Vercel.

A member of the Team first needs to authorize it.