fix(mcp): use request fetch for raw page content

[onmax]

Follow-up to #1302.

Summary

get-page now derives its url from the incoming request origin, which is correct for proxied and deployed environments. The remaining problem is that it still fetches its markdown body through an absolute self-request.

That works locally, but on Cloudflare Workers the same-worker subrequest returns 404, so list-pages works while get-page fails with Failed to get page.

This keeps the request-origin URL behavior but switches the content fetch to event.$fetch('/raw${path}.md'), which resolves through Nitro's request-bound fetch path instead of an outbound absolute request. That preserves the existing raw markdown response shape and avoids reconstructing markdown from parsed content data.

Reproduction

Variant	Source	Deployed worker	Result
Bug	onmax/repros/docus-mcp-get-page-worker-repro	docus-mcp-get-page-repro.je-cf9.workers.dev	get-page returns Failed to get page
Fix	onmax/repros/docus-mcp-get-page-worker-repro-fix	docus-mcp-get-page-repro-fix.je-cf9.workers.dev	get-page returns the raw markdown content

Verify

Broken worker:

curl -sS \
  -H 'accept: application/json, text/event-stream' \
  -H 'content-type: application/json' \
  -X POST https://docus-mcp-get-page-repro.je-cf9.workers.dev/mcp \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"get-page","arguments":{"path":"/test"}}}'

Fixed worker:

curl -sS \
  -H 'accept: application/json, text/event-stream' \
  -H 'content-type: application/json' \
  -X POST https://docus-mcp-get-page-repro-fix.je-cf9.workers.dev/mcp \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"get-page","arguments":{"path":"/test"}}}'

Local source verification:

pnpm typecheck

[vercel]

@onmax is attempting to deploy a commit to the NuxtLabs Team on Vercel.

A member of the Team first needs to authorize it.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/create-docus@1304

npm i https://pkg.pr.new/docus@1304

commit: d200ef5