Preserve scroll position on configuration changes in MessageList

[andremion]

🎯 Goal

Preserve scroll position during configuration changes in the MessageList by preventing automatic scroll-to-bottom behavior when the same new message state is restored after a configuration change.

🛠 Implementation details

• Introduces state preservation logic using rememberSaveable to track the last new message state that triggered scroll-to-bottom
• Adds custom Saver implementations for NewMessageState and MutableState<NewMessageState?> to handle serialization across configuration changes
• Modifies scroll-to-bottom logic to only trigger when the new message state differs from the previously saved state

🎨 UI Changes

Before	After
Screen.Recording.2025-10-10.at.09.43.07.mov	Screen.Recording.2025-10-10.at.09.42.18.mov

🧪 Testing

• Given that the last message is the current user's message.
• Scroll far from the bottom in the message list, then rotate the screen.
• Scroll far from the bottom in the message list, start and stop typing from the other chat member.
• Scroll far from the bottom in the message list, type and send a message.

[Copilot]

Pull Request Overview

This PR preserves scroll position during configuration changes in the MessageList by preventing automatic scroll-to-bottom behavior when the same new message state is restored after a configuration change.

• Introduces state preservation logic using rememberSaveable to track the last new message state that triggered scroll-to-bottom
• Adds custom Saver implementations for NewMessageState and MutableState<NewMessageState?> to handle serialization across configuration changes
• Modifies scroll-to-bottom logic to only trigger when the new message state differs from the previously saved state

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[github-actions]

SDK Size Comparison 📏

SDK	Before	After	Difference	Status
stream-chat-android-client	3.22 MB	3.22 MB	0.00 MB	🟢
stream-chat-android-offline	3.45 MB	3.45 MB	0.00 MB	🟢
stream-chat-android-ui-components	10.54 MB	10.54 MB	0.00 MB	🟢
stream-chat-android-compose	12.75 MB	12.75 MB	0.00 MB	🟢

[sonarqubecloud]

Quality Gate failed

Failed conditions
46.9% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud