Add layers, groups, directional transitions, toggles, custom colors and Chinese

- Icon picker: the list now appears on the first open (memo missed the glyph pass)
- Top app bar / navigation bar: drop the status bar and gesture handle contents, keep heights
- Transitions: slide from any of four sides, "back" as a target, reverse playback on back
- Per-slot tap targets on bar icons and destinations; arrows and preview hit areas follow
- Preview: finger-tracked frame swipes, live sliders, toggle buttons, bottom control bar
- Prompt: explicit rows and layered containers, bottom sheet only when the handle is on,
  a fixed no-emulator / release-APK line, Chinese output
- Toggle buttons with an on-state label, icon and style edited through tabs
- Layers panel with drag reorder, free groups that keep overlap and move together
- Deleting a screen removes its parts and links; clear-all asks first
- Color tab: presets, seed-based custom scheme with fine-tuning, dynamic color switch
- Left rail with parts / layers / colors, language menu and GitHub link; language icon
  and sheet on phones, Chinese added
- PNG export rendered offscreen at 1:1, list item backgrounds, corner icons, box defaults
- README in three languages and refreshed screenshots

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>