Fix Android pinch pointer lift handling

[sorinc03]

Summary

• end an active Android pinch when a pointer lift leaves fewer than two tracked pointers
• fail a begun-but-not-active pinch in the same case
• avoid emitting an extra active pinch update with stale numberOfPointers / focal data after one finger is lifted

Fixes #3435.

Test plan

• yarn workspace react-native-gesture-handler lint:android
• ./gradlew :app:assembleDebug --console=plain -PreactNativeArchitectures=arm64-v8a from apps/basic-example/android

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Fixes pinch gesture handler on Android to end/cancel when the pointer count drops below the minimum required (2) due to a pointer being lifted, not just on the final ACTION_UP.

Changes:

• Detect when a pointer-up event reduces active pointers below MIN_POINTERS.
• Trigger state transition (cancel/end) in that case alongside ACTION_UP.
• Introduce MIN_POINTERS companion constant.

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[j-piasecki]

Hey! Thanks for bringing it to our attention. Your PR would cause Pinch gesture to fail when left with a single pointer, which would cause its behavior to diverge from iOS and Web implementations.

I've looked a bit more into this, and it's a general issue with all handlers where, on ACTION_POINTER_UP, Android includes the lifted pointer in the event's pointerCount. I've opened #4218 to address the underlying problem. If this was affecting you, I'd appreciate if you could check whether that PR solves the problem for you.