Update tui.mdx with Device, Stream, and Config screen sections
including keyboard shortcuts, Tabs/Steps components, and safety
warnings. Update generate_screenshots.py to capture all 11 screens.
Regenerate all SVGs with current sidebar layout.
- New docs page (tools/tui.mdx) covering all 5 RF modes, keyboard
shortcuts, easter eggs, and splash screen with inline SVG screenshots
- Screenshot generation script using Textual headless Pilot API to
capture 8 screens in demo mode without hardware
- Fix dark mode toggle: migrate from removed App.dark to App.theme API
(Textual 7.x breaking change)
- Update social link to Gitea repo, add TUI to sidebar
