Remove the broken "Connect Claude" / "Reconnect Claude" buttons from
the Plan pane -- they opened a terminal session that did nothing useful
for already-logged-in users. Keep only the "Retry" button.
Add an auto-update checker that queries GitHub releases every 2 days in
the background. When a newer menubar build is available, an "Update"
pill appears in the header. Clicking it runs the existing installer
flow (download, replace, relaunch) with no manual steps.
