- Smart auto-scroll: only follow SSE stream when user is near bottom (200px threshold), scroll once on send/switch session
- Brighten dark mode text colors (primary #e0→#f0, secondary #a0→#c0, muted #66→#88)
- Fix tool-call panel height to match thinking video (120px→213px)
- Fix tool-call item background invisible in dark mode
- Fix gateway start button using hardcoded dark color
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Implement runtime theme switching using CSS custom properties delegated through SCSS variables, with light/dark/system modes, FOUC prevention, sidebar toggle, and settings selector. Add theme-aware video assets for sidebar and chat thinking indicator.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>