docgen-server is the dev-only server behind docgen dev: an axum app
(bound to 127.0.0.1 only) that serves the built site, watches docs/ for
changes (debounced), rebuilds via [docgen_build::build_site], pushes a
live-reload signal over SSE, and exposes a path-guarded markdown write
endpoint for the in-browser editor.
Nothing in this crate ships in a static docgen build dist: the editor UI,
the reload client, the write/SSE endpoints, and the vendored CodeMirror
assets exist ONLY while this server runs.