fix: correct scroll position when closing keyboard on mobile

[Linhead]

Description

Fixed incorrect scroll position adjustment in chat when closing mobile keyboard. The resizeHandler in AChat.vue was applying scroll correction regardless of viewport resize direction, causing the chat to scroll up ~4-5 messages when keyboard closes.

Changes:

• Added condition clientHeightDelta > 0 to only adjust scroll when viewport shrinks (keyboard opens)
• Preserved scroll position when viewport expands (keyboard closes)
• Single-line change following Open-Closed principle for minimal regression risk

Related issue

Closes #886

Breaking changes

No

How to test

Prerequisites

• Test on older Android device (Samsung A10/A11/A12/A13) or device with Chrome WebView < 108
• Or use BrowserStack/similar service for older Android versions

Test Steps

Test Case 1: Basic keyboard close

1. Open any chat dialog with 10+ messages
2. Tap message input field to open keyboard
3. Send 5 short text messages (e.g., "test 1", "test 2", etc.)
4. Close keyboard by tapping on message area

Expected: Last sent message ("test 5") is visible at bottom
Actual before fix: Last message is hidden, need to scroll down manually

Test Case 2: Scrolling with keyboard open

1. Open chat with 20+ messages
2. Tap input field to open keyboard
3. Scroll up to read older messages
4. Close keyboard

Expected: Scroll position preserved at the same messages
Actual before fix: Scroll jumps up further, hiding more messages

Test Case 3: Rapid message sending

1. Open chat dialog
2. Tap input field
3. Rapidly send 10 messages without closing keyboard
4. Close keyboard

Expected: Last message visible
Actual before fix: Last ~4 messages hidden

Notes for reviewers

Highlight anything important that reviewers should pay attention to.
(e.g. tricky logic, potential side effects, performance considerations)

Checklist

• Code is formatted
• Tests added/updated (if needed) - no need
• Documentation updated (if needed) - no need
• Changes tested in all relevant environments - I could not reproduce it on my device

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Project	Deployment	Preview	Comments	Updated (UTC)
adamant-im	Ready	Preview	Comment	Oct 6, 2025 3:43pm

[github-actions]

Deployed to https://msg-adamant-pr-887.surge.sh 🚀

[metalisk]

primarily older Android devices like Samsung A12

I propose ignoring (especially) not critical bugs on old devices to be more effective and not to maintain legacy.

If this bug affects only old devices, and fix doesn't work, let's close the issue without a solution.