This fixes panics introduced in 2412adf42b
when Gin ungracefully assumes that the http.ResponseWriter implements
http.CloseNotifier and http.Flusher, which our new statusCodeRecorder
does not. This is a temporary fix until we can pour the rest of the Gin
out.
This commit introduces a new API implementation for handling
interactions with the registry and the local model cache. The new API is
located in server/internal/registry. The package name is "registry" and
should be considered temporary; it is hidden and not bleeding outside of
the server package. As the commits roll in, we'll start consuming more
of the API and then let reverse osmosis take effect, at which point it
will surface closer to the root level packages as much as needed.