fix: prevent parent Pressable from firing onPress on link/task tap

[hryhoriiK97]

What/Why?

Fixes: #142

Tapping a markdown link inside a Pressable fires both onLinkPress and the parent's onPress. This PR prevents the parent from receiving the tap when the user taps a link or task list checkbox.

• iOS: Override touchEventEmitterAtPoint: to return nil on interactive elements, preventing JS touch dispatch entirely.
• Android: Call NativeGestureUtil.notifyNativeGestureStarted to cancel the JS gesture. A brief opacity flash on the parent is unavoidable due to how Android Fabric dispatches touchStart before child views receive the touch — same limitation as RN's own ScrollView.

Why not e.stopPropagation()?

onLinkPress is a custom native event, separate from the touch/responder system that powers Pressable. stopPropagation() only affects the onLinkPress bubble — it has no effect on native touch dispatch, which must be intercepted at the platform level.

Testing

PR Checklist

• Code compiles and runs on iOS
• Code compiles and runs on Android
• Updated documentation/README if applicable
• Ran example app to verify changes