Deletes the hand-rolled AuthContext/UserManager setup and replaces it
with AuthProvider from react-oidc-context. onSigninCallback clears the
OIDC code params from the URL (unless an error is present). TokenSync
bridges the library token into the existing api/client setTokenProvider
pattern. AuthGuard updated to use auth.isLoading/isAuthenticated/
signinRedirect from the library. CallbackPage simplified to a passive
error renderer — react-oidc-context processes the OIDC exchange itself.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Spencer Twaddle
b33ff5079c