fix: highlight same-net traces on hover

[kitwongpixel]

Fixes #1130

Summary

• Adds a useTraceHoverHighlight hook in schematic-viewer
• Highlights all schematic trace groups with the same connectivity key when one trace is hovered
• Adds a dedicated fixture for manual verification: example21-connected-trace-hover.fixture.tsx

Verification

• git diff --check
• npx biome check lib/components/SchematicViewer.tsx lib/hooks/useTraceHoverHighlight.ts examples/example21-connected-trace-hover.fixture.tsx
• npx -p typescript@5.9.2 tsc --noEmit -p tsconfig.json

Demo Video

• https://github.com/kitwongpixel/schematic-viewer/releases/tag/demo-trace-hover-1130

Notes

• This keeps the fix localized to the viewer layer and does not change the SVG generation pipeline.

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Project	Deployment	Actions	Updated (UTC)
schematic-viewer	Ready	Preview, Comment	May 30, 2026 5:32am

[kitwongpixel]

Demo video for the fix: https://github.com/kitwongpixel/schematic-viewer/releases/tag/demo-trace-hover-1130

The video is a browser recording of the fixture showing same-net trace hover highlighting.