fix(ui): skip per-frame re-renders on the swatch tray

[cameronapak]

Summary

Swatch-tray fades still appear and retire at the same remaining-distance gates, but a drag no longer re-renders the verse action sheet every frame.

Changes

1. Fade overlays mount from overflow booleans, not the live scroll offset — layout and offset live in refs, React only stores the two gates.
2. A layout pass mid-scroll still sees the current offset, so both fades stay put while the tray remeasures.

Test plan

• pnpm --filter @youversion/platform-react-native-expo-ui test -- src/native/__tests__/bible-reader-verse-actions.test.tsx (27 passed)
• npx react-doctor@latest --scope changed — rn-no-scroll-state is gone
• Needs manual check: swipe an overflowing swatch tray on device; leading and trailing fades still appear and retire at the ends

Made with Cursor

Greptile Summary

The PR extracts swatch-tray fade arithmetic into a tested helper and stores live measurements in refs so scrolling updates React only when an edge-visibility gate changes.

• Adds focused tests for the fade thresholds and remaining-distance calculations.
• Preserves the current scroll offset when layout measurements arrive mid-scroll.
• Avoids updating component state with the raw offset on every scroll event.

Confidence Score: 5/5  · 

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
packages/ui/src/lib/verse-action-fade-gates.ts	Defines the shared, pure calculation for leading and trailing fade visibility.
packages/ui/src/lib/tests/verse-action-fade-gates.test.ts	Covers fitting, overflowing, midpoint, endpoint, and one-pixel threshold behavior.
packages/ui/src/native/bible-verse-action-sheet.tsx	Moves live tray dimensions and offset into a ref while retaining only fade visibility booleans in React state.
packages/ui/src/native/tests/bible-reader-verse-actions.test.tsx	Adds coverage ensuring a layout pass during an active scroll preserves both applicable fades.

_{Reviews (2): Last reviewed commit: "refactor(ui): extract swatch tray fade g..." | Re-trigger Greptile}

[bmanquen]

Two-axis review (Standards + Spec) against HEAD~1.

Standards: no hard violations. ADR 0017's load-bearing decisions are all intact — the fade still gates on remaining scroll distance, modal={false} and PAN_ACTIVE_OFFSET_Y are untouched, the sheet stays internal, and the explanatory comment block was preserved rather than dropped. No new user-visible strings, so .greptile/rules.md / native-i18n.md don't bite, and .changeset/native-highlights-release.md already covers the sheet.

Spec: not run — no issue reference in the commit, no spec file matching the branch.

Six judgement calls inline, all non-blocking. The one worth acting on is the first: swatchTrayFadeGates is a pure predicate sitting in the component, which is why its only coverage has to boot the whole BibleReader.