[General] Change how gestures are attached to the native detector to fix StrictMode

[j-piasecki]

Description

1. Changes Module.createGestureHandler to be asynchronous
2. Changes NativeProxy.createGestureHandler to use the same scheduling as drop to preserve relative ordering
3. Moves the creation of the native handler to the effect from the render phase
4. Updates the native implementations of GestureDetector not to rely on synchronous creation of gesture handlers. Instead, introduces the ability to register a callback to be fired once a gesture is created. This way, the detector can attach gestures as they are created on the native side with no dependency on JS (the only required thing is the relative ordering of create and drop operations, so create -> drop -> create isn't run as create -> create -> drop.

Test plan

Use the example app.

[Copilot]

Pull request overview

This PR changes gesture handler creation/attachment so native detectors no longer depend on synchronous handler creation, aiming to support React StrictMode ordering.

Changes:

• Defers native handler creation and aligns it with the scheduled operation queue.
• Adds observer/ready-callback registries for web, Android, and iOS.
• Updates native/web detector attachment flows to subscribe to handler creation and attach once handlers are available.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/react-native-gesture-handler/src/web/tools/NodeManager.ts	Adds handler existence checks and observer registration/cancellation.
packages/react-native-gesture-handler/src/v3/NativeProxy.ts	Schedules handler creation through the flush queue.
packages/react-native-gesture-handler/src/v3/hooks/useGesture.ts	Moves native handler creation from render to an effect.
packages/react-native-gesture-handler/src/v3/detectors/HostGestureDetector.web.tsx	Reworks web detector attachment around handler readiness observers.
packages/react-native-gesture-handler/src/specs/NativeRNGestureHandlerModule.ts	Changes createGestureHandler codegen signature from sync boolean to void.
packages/react-native-gesture-handler/src/RNGestureHandlerModule.web.ts	Makes web relation configuration tolerate missing handlers.
packages/react-native-gesture-handler/apple/RNGestureHandlerRegistry.h	Declares ready-callback observer APIs for iOS.
packages/react-native-gesture-handler/apple/RNGestureHandlerRegistry.m	Implements iOS handler observer storage and notification.
packages/react-native-gesture-handler/apple/RNGestureHandlerModule.mm	Defers iOS handler creation into operation blocks.
packages/react-native-gesture-handler/apple/RNGestureHandlerDetector.mm	Reworks iOS detector subscriptions and attachment to use ready callbacks.
packages/react-native-gesture-handler/android/src/main/java/com/swmansion/gesturehandler/react/RNGestureHandlerRegistry.kt	Adds Android observer registration/cancellation and ready notifications.
packages/react-native-gesture-handler/android/src/main/java/com/swmansion/gesturehandler/react/RNGestureHandlerModule.kt	Updates Android create method signature to void.
packages/react-native-gesture-handler/android/src/main/java/com/swmansion/gesturehandler/react/RNGestureHandlerDetectorView.kt	Reworks Android detector subscription/attachment lifecycle around handler readiness.

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[j-piasecki]

I know, I wanted to handle it in a follow-up to keep changes as small as possible