M3E Canvas: Material 3 Expressive screen editor with prompt output

Drag-and-drop M3 Expressive parts, magnetic connected groups, multiple phone
screens with tap-to-navigate links and a tap-through preview, shape-morphing
loading indicator and wavy progress ported from material-components-android,
Japanese/English UI and prompt generation, alignment guides, undo/redo,
localStorage persistence, a lightweight phone mode, and a static export
deployed to GitHub Pages via Actions.

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