feat: add SSR documentation and tanstack start docs

[swalker326]

What's added in this PR?

• Added a TanStack Start docs page that documents the Zephyr integration for Cloudflare-based TanStack Start projects created via the TanStack Start CLI: install vite-plugin-tanstack-start-zephyr, add withZephyrTanstackStart() to vite.config.ts, then run npm run build to deploy.
• Added upstream reference links so users can follow the official setup flows:
  • TanStack Start CLI quick start: TanStack Start (React) Quick Start
  • Cloudflare Workers TanStack Start setup: Cloudflare Workers: TanStack Start
• Added SSR Worker (beta) documentation explicitly stating:
  • Cloudflare-only
  • Only supported on Zephyr’s default (managed) Cloudflare integration
  • Not available on Bring Your Own Cloud (BYOC)
• Updated docs navigation to include the new pages and added a Cloudflare guide callout linking to the new SSR Worker + TanStack Start docs.

What's the issues or discussion related to this PR (optional) ?

Users creating TanStack Start projects via the CLI and choosing Cloudflare needed a single, Zephyr-specific place to learn the minimal steps to deploy (plugin + build), plus clear documentation of the SSR Worker’s current beta and provider limitations. This PR adds those docs and cross-links them from the Cloudflare integration guide.

Feature related update for this PR (if applicable)?

• New docs pages:
  • /meta-frameworks/tanstack-start
  • /reference/ssr-worker
• Cloudflare guide now includes an SSR Worker availability callout and links.

Who do you wish to review this PR other than required reviewers?

(Required) Pre-PR/Merge checklist

• I have added/updated our feature to sync with this PR
• I have added an explanation of my changes
• I have/will run tests, or ask for help to add test

[github-actions]

🚀 Preview Environment Ready!

Name	Status	URL
zephyr-cloud-docs	✅ Active	https://zackary-chapple-11841-zephyr-cloud-docs-zephyr-do-99892b7... ↗

Details:

• Latest Commit: d78c45d
• Updated at: 12/13/2025, 2:24:59 PM