🎨 Palette: Fix TalkBack accessibility on decorative and close images

[LeanBitLab]

💡 What: Added android:contentDescription attributes to UI elements.
🎯 Why: To improve screen reader navigation by ensuring interactive buttons (like the emoji palette close button) have accurate descriptions, and purely decorative images (like the clipboard icon and inline search icon) are ignored by tools like TalkBack to reduce audio clutter.
♿ Accessibility: Significant improvement for visually impaired users.

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PR created automatically by Jules for task 15910797321590353913 started by @LeanBitLab

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