* Fix CJK text garbled when font unavailable (#69)
Always use buildParagraph for text rendering when fonts are loaded,
even when the node's specific font isn't available. The paragraph
shaper falls back to the CJK font in fontFamilies, instead of the
previous drawText fallback which used Inter (no CJK glyphs).
* Add renderText unit tests for CJK font fallback behavior
* Add CJK visual regression test with Noto Sans SC fixture
- Download NotoSansSC-Regular.ttf as LFS-tracked test fixture
- Add setCJKFallbackFamily() export for headless/test use
- Visual test verifies CJK text renders through buildParagraph fallback
when node font is unavailable (the exact PR #89 scenario)
- Assert dark pixel count > 500 to distinguish real glyphs from tofu
Replace BFS (which skipped DSD-modified nodes in visited set, breaking
the chain for deeper clones) with iterative convergence loop. Track
dsdSizeSet separately from dsdModified so nodes with only position/
geometry changes inherit size from their source.
Fix transitive override propagation: re-clone from source (not component)
to preserve componentId chain for DSD. Add syncChildrenDeep for deep
property propagation (stroke colors on nested vectors).
Reduces vector overflow in gold-preview.fig from 25 to 0 (visible,
unclipped).
