feat: expose onEndVisible callback from KeyboardChatScrollView

[kirillzyusko]

📜 Description

Added onEndVisible callback for KeyboardChatScrollView.

💡 Motivation and Context

Originally these changes were requested in #1430 for implementing functionality like "jump-to-end". I kind of agree, that we were computing the isAtEnd internally, so technically it's really not so difficult to expose it outside and it's really useful to have a logic for controlling lift behavior and end detection unified/reusable/the same.

So in this PR I'm adding this callback. It has support for both worklet and plain JS function.

Closes #1431 #1430

📢 Changelog

JS

• added onEndVisible callback to KeyboardChatScrollView;

Docs

• added documentation about onEndVisible callback;

🤔 How Has This Been Tested?

Tested on iPhone 17 Pro (iOS 26.2).

📸 Screenshots (if appropriate):

📝 Checklist

• CI successfully passed
• I added new mocks and corresponding unit-tests if library API was changed

[github-actions]

📊 Package size report

Current size	Target Size	Difference
317457 bytes	314410 bytes	3047 bytes 📈

[github-actions]

PR Preview Action v1.8.1
Preview removed because the pull request was closed.
2026-05-04 08:02 UTC

[argos-ci]

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Build	Status	Details	Updated (UTC)
default (Inspect)	👍 Changes approved	1 changed	May 4, 2026, 7:24 AM

[github-actions]

1. Missing null/undefined check before calling runOnJS
   Why: If onEndVisible is undefined (e.g., not provided by parent component), calling runOnJS(onEndVisible) will pass undefined to a function expecting a function reference, potentially causing runtime errors.
   Fix: Add a null/undefined check before invoking runOnJS.

2. Potential undefined function passed to runOnJS
   Why: In useEndVisible.ts, the onEndVisible prop is not validated, leading to possible undefined being passed to runOnJS.
   Fix: Ensure onEndVisible is defined before using it in useEndVisible.