[Web] Fix Pressable not calling onPress* callbacks

[m-bert]

Description

#4108 introduced another condition for activation of Native gesture. Since Pressables use PureNativeButton, not RawButton, they do not meet this condition, hence they don't activate

Test plan

Pressables examples in expo-example

[Copilot]

Pull request overview

Fixes web Pressable not firing onPress* callbacks by ensuring the underlying Native gesture activates immediately on web (matching the activation condition introduced in #4108).

Changes:

• Set shouldActivateOnStart: Platform.OS === 'web' for the v3 Pressable native gesture.
• Set .shouldActivateOnStart(Platform.OS === 'web') for the legacy Pressable Gesture.Native() instance.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/react-native-gesture-handler/src/v3/components/Pressable.tsx	Enables start-activation for the native gesture on web so Pressable can transition to ACTIVE and trigger callbacks.
packages/react-native-gesture-handler/src/components/Pressable/Pressable.tsx	Applies the same start-activation behavior for the legacy Pressable implementation on web.

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