fix: update hydrogen link to point to correct page

The Cloudflare index page was linking to `frameworks/hydrogen/` which
doesn't exist, causing 404s. Updated to point to the correct
`hydrogen-react-router/` page for current Hydrogen versions.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: codyde

docs/platforms/javascript/guides/cloudflare/index.mdx

@@ -13,7 +13,7 @@ Use this guide for general instructions on using the Sentry SDK with Cloudflare.
 
 - **[Astro](frameworks/astro/)**
 - **[Hono](frameworks/hono/)**
-- **[Hydrogen](frameworks/hydrogen/)**
+- **[Hydrogen](frameworks/hydrogen-react-router/)**
 - **[Nuxt](frameworks/nuxt/)**
 - **[Remix](frameworks/remix/)**
 - **[SvelteKit](frameworks/sveltekit/)**