`http.post` attaches the user's Authorization header to any same-origin
path the plugin's own manifest lists in `apiPostPaths`. A plugin with
only `http:post` could list the JMAP passthrough and get full JMAP
access, or reach `/api/admin/*`, `/api/settings` and the other
credentialed routes. The host now refuses those paths whatever the
manifest says, checked on the decoded path the router sees. Plugins
keep reaching their own sidecar routes.