- Fix axis mapping for nested frames with different layout directions
(e.g. vertical child inside horizontal parent had swapped sizing)
- Fix stretch alignment not applying to leaf children when set on parent
- Fix layoutGrow being ignored on children with FIXED primaryAxisSizing
- Add 42 unit tests covering all layout scenarios
Document structure: Document (root) → Pages (CANVAS) → Nodes.
Each page has its own viewport (pan/zoom) and background color.
- CANVAS node type for pages
- SceneGraph: addPage(), getPages(), getAbsolutePosition stops at CANVAS
- Store: currentPageId, switchPage(), addPage(), deletePage(), renamePage()
- All operations (create, select, paste, hit test, render) scoped to current page
- Per-page viewport state saved/restored on page switch
- Pages list in LayersPanel with add/switch/double-click rename
- .fig import creates proper pages from DOCUMENT→CANVAS hierarchy
- Renderer takes pageId to render correct page's children
- Unit test for pages, updated E2E tests for page-scoped graph
