LiveDocs: fetch_docs/introspect fetch client-supplied URLs with no host allowlist and follow redirects

LiveDocs is a primary-source-first documentation for AI agents. Prior to version 0.7.0, fetch_docs and introspect (kinds openapi/graphql, and resolve_source's docs_url) pass a client-supplied URL straight to URLSession with no scheme or host allowlist, and redirects are followed unconditionally. A prompt-injection payload embedded in fetched documentation can steer the model to call fetch_docs against internal or metadata endpoints and stream the response back into the conversation. This issue has been patched in version 0.7.0.