🎨 Palette: Add accessibility attributes to text share popover

[hadsern]

💡 What: Added aria-label and focus-visible ring styles to the icon-only buttons in the TextSharePopover.
🎯 Why: Ensure these interactive elements provide clear context to screen readers and show explicit visual focus indicators during keyboard navigation, improving overall accessibility.
♿ Accessibility:

• Added aria-label attributes dynamically matching titles.
• Applied focus-visible:ring-2 to support keyboard-only users.

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PR created automatically by Jules for task 1945100216206112087 started by @hadsern

[google-labs-jules]

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