feat: add semantic line gaps

[brandtnewlabs]

Summary

• add lineGaps with shared renderer-neutral ChartGap* types
• split line stroke, area/gradient, dot-lattice, and threshold fills across declared gaps, with configurable prior-value bridges, bands, and labels
• extend scrubbing and tooltips with semantic gap context while letting real samples override gap metadata
• expand the live Chart gaps demo to switch between moving line and candle charts and showcase bridge, band, label, and color controls
• document the public API and add focused rendering, path, crosshair, and component coverage

Testing

• npm run verify — 108 suites passed; 1,622 tests passed, 5 skipped
• npm run build:lib
• CI=1 npx react-doctor@latest --verbose --diff — 96/100; only existing/required maintainability warnings
• agent-device on iPhone 17 Pro simulator — verified moving live line data, raw/semantic/styled treatments, bridge and band toggles, and candle + volume + trade-stream regression; no runtime or worklet errors

Stack

• depends on Add semantic candle gaps and configurable live demo #286

[brandtnewlabs]

• feat: add semantic line gaps #287 👈 (View in Graphite)
• Add semantic candle gaps and configurable live demo #286
• main

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