The auth button derived from stores that hydrate in stages, so it
flashed through Login -> Dashboard -> Go to LMS as isLoggedIn and the
role/basePath settled at different times. Gate the label on
appInitApi.isInitializedAndReady so it only renders once the account
(and thus role) has loaded, and show a spinner in the button while a
logged-in user's experience resolves. Add separate loading and disabled
flags to authAction and wire them through all theme navs.