Fix candle width after line mode timeframe switch

[brandtnewlabs]

Fixes #273.

What changed

• keep the candle-width frame callback started for every non-static LiveChart, independent of its mount-time mode
• guard width interpolation at runtime so line mode stays idle while preserving the latest candleWidth target
• add regressions for a chart mounted as a line, updated to a new timeframe, and then switched to candles
• document the fix in the Unreleased changelog

Root cause

useFrameCallback seeds its active state from autostart only on the initial render. Gating autostart with isCandle therefore left the callback permanently inactive when a chart mounted in line mode, so its displayed candle width stayed pinned to the initial value.

Before / after

The matching iOS Simulator recordings use this sequence: 1D · LINE → 1M · LINE → 1M · CANDLE.

Before

issue-273-before.mp4

After

issue-273-after.mp4

Validation

• npm run verify — typecheck, lint, 103 Jest suites / 1,576 passing tests
• npx react-doctor@latest --verbose --diff — 100/100, no issues
• iOS Simulator reproduction on iPhone 17 Pro / iOS 26.5