Replace eager login verification on startup with assumeLoggedIn(),
which sets login state from saved credentials without any network call.
Real verification is deferred until sync (which needs the actual user ID)
or when the settings page is opened.
- UserComponent: add verified flag, assumeLoggedIn(), isVerified()
- main.ts: replace onLayoutReady(login) with assumeLoggedIn(); fix
inverted condition bug in checkLogin() (!needLogin -> needLogin)
- DoubanSyncModal: remove redundant login check before checkLogin()
- LoginSettingsHelper: handle assumed-but-unverified state in constructLoginUI()
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
