- Add missing modal CSS (.modal-overlay/.modal-dialog/.modal-header):
the "Connect to Microsoft" auth modal was rendering unstyled inline
at the bottom of the page. Now a centered dialog with backdrop.
- Surface OAuth connect errors in the modal instead of silently
reopening it with no explanation.
- MainLayout: implement IDisposable so event handlers are actually
unsubscribed (Dispose existed but was never invoked).
- Wire up the Settings theme selector (was a dead control): drop the
unsupported Dark option, call sptb.setTheme on save and on load,
resolve System via prefers-color-scheme.
- Add branded 404 page via UseStatusCodePagesWithReExecute + Routes
<NotFound> (blank white page before).
- Add .progress-fill.indeterminate animation and .progress-panel.
- Home: replace inline JS hover handlers with a .feature-card CSS class.
- Define missing --surface-2 variable referenced by MainLayout.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
kawa