TokenPicker uses SwipeDismissHandle primitive (polish wave C.1)

[epicexcelsior]

Summary

`POLISH_PLAN.md` Wave C.1 called for extracting an inline pan-to-dismiss gesture from `TokenPicker.tsx` into a reusable primitive at `components/primitives/SwipeToDismiss.tsx`. Audit found the primitive already exists as `components/primitives/SwipeDismissHandle.tsx` — exported from the index, but never used anywhere. `TokenPicker` carried an inline duplicate of the same logic.

This PR refactors `TokenPicker` to consume the existing primitive. No new file, no architecture change — just dedupe.

What changed

• `mobile_app/components/send/TokenPicker.tsx` — drops the local `panGesture` / `dismiss` callback / `Gesture` + `runOnJS` + `withSpring` imports / `DISMISS_DISTANCE` + `DISMISS_VELOCITY` constants. Imports `SwipeDismissHandle` from `@/components/primitives`. The handle component renders its own grab indicator + gesture-capture area, so the in-line decorative grab bar at the top of the sheet was also dropped (replaced by the handle render).
• 33 LOC removed net (160 deletions − 127 insertions).

Architecture note worth surfacing

The pre-existing `SwipeDismissHandle` captures pan on the handle area only, not the whole sheet. Per its own docstring:

Using a dedicated handle avoids the scroll-conflict issue of wrapping full screen content in a Pan gesture — only the handle itself captures the gesture; child scrollviews + pressables work normally.

The previous `TokenPicker` implementation wrapped the entire sheet in `GestureDetector` — fine for that screen since it has no `ScrollView`, but the wrong template for the audit. Modals with internal scrollables (`TxDetailModal`, `ExportWalletModal`, recovery key reveal, receive QR) can adopt this same pattern cleanly post-merge.

Drive-by

Carries the same `fix(nodes): drop stale H_PAD reference` cherry-pick the other open wallet-lane PRs do — `tsc --noEmit` errors out on `upstream/v3` without it. No-ops on whichever PR merges first.

Validation

• `npx tsc --noEmit` clean
• `npm run lint` clean
• `npm run validate:tier0:services` pass
• `node ./scripts/validate-tier0-config.mjs` pass

Test plan

• Send flow on Seeker: open `/send/recipient` → tap token chip → TokenPicker sheet slides up
• Pan down on the handle area → sheet follows finger
• Release past threshold (120pt or velocity > 800) → sheet dismisses
• Release short → sheet springs back
• Tap a token → selection works (haptic + sheet dismiss)
• Tap close icon → sheet dismisses
• Tap backdrop → sheet dismisses

Future work (not this PR)

Apply `SwipeDismissHandle` to:

• `TxDetailModal` (post PR Improve wallet activity: SPL symbols, decimals, tap-to-detail #31 merge — different branch)
• `ExportWalletModal` recovery key reveal (post PR Recovery export hardening: screen-capture failsafe + inline error surface + Solana Pay locale comma #30 merge)
• Receive QR (`ReceivePanel`)
• Settings modals (D-lane, needs Djason heads-up)

[epicexcelsior]

Superseded by upcoming PR — proper @gorhom/bottom-sheet primitive replaces SwipeDismissHandle and migrates TokenPicker + receive screen as a single product truth. The H_PAD cherry-pick lives on PR #30 / #31 anyway.