GeezerVison

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• The PR title follows our guidelines: https://github.com/NativeScript/NativeScript/blob/master/tools/notes/CONTRIBUTING.md#commit-messages.
• There is an issue for the bug/feature this PR is for. To avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it.
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• All existing tests are passing: https://github.com/NativeScript/NativeScript/blob/master/tools/notes/DevelopmentWorkflow.md#running-unit-tests-application.
• Tests for the changes are included - https://github.com/NativeScript/NativeScript/blob/master/tools/notes/WritingUnitTests.md.

What is the current behavior?

Renderers such as React and DOMiNATIVE swap an event handler by removing the old listener and adding the new one, which for an inline arrow function happens on every render, often in response to the gesture itself. Each gesture listener owns its own GesturesObserver, so removing it tears down the native recognizer (the UIGestureRecognizer on iOS, the gesture detector on Android), and adding the new one creates a recognizer that never saw the touch in progress. A handler that sets state on down gets no move or up after it, so sliders and charts only ever see the first event. Pan, pinch and the other gestures lose the gesture the same way.

What is the new behavior?

• Removing a gesture listener stops calling it at once, but keeps its observer and native recognizer until the next turn.
• A listener for the same gesture added before then takes over that observer (GesturesObserverBase._setCallback, internal) instead of creating a new one, so it receives the rest of the gesture.
• Observers that are not taken over are disconnected in the next turn, as before. getGestureObservers() reflects a removal immediately.
• On iOS, UIGestureRecognizerImpl.recognize() calls the owner's current callback with the owner's current context.

Tests: ui/core/view/gesture-observers.spec.ts (6): the recognizer is kept across a swap, the new listener receives the in-progress gesture with the right this, a removed listener is silent immediately, an unused recognizer is removed in the next turn, observers are not reused across gesture types. apps/automated gains test_swapping_touch_listener_keeps_native_recognizer (iOS) and test_swapping_gesture_listener_reuses_observer.

Verified with all of these core PRs merged together (#11527–#11537): apps/automated passes on the iOS 26.4 simulator (1830 OK, 0 failed) and on an Android API 36 emulator (1692 OK; the one failure is the network-dependent IMAGE-CACHE.test_ImageCache_ValidUrl timeout, which also passes on reruns).