🎨 Palette: Improve AppDiagnosticsView UX and Accessibility

[emkey1]

💡 What:

• Wrapped copiedReport state changes in withAnimation blocks for smooth transient text transitions.
• Added dynamic accessibilityLabel to the "Copy Report" button based on its transient state.
• Added accessibilityHints to both the "Copy Report" and "Run Diagnostics" buttons.

🎯 Why:

• Transient visual states appearing and disappearing abruptly can feel unpolished. withAnimation provides a graceful transition.
• Screen reader users were previously missing context on what the icon-only buttons do, and state changes weren't being announced, reducing the interface's accessibility.

♿ Accessibility:

• Added context via VoiceOver hints.
• Ensured state changes on the copy button are dynamically represented in VoiceOver labels.

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PR created automatically by Jules for task 1884646995970992144 started by @emkey1

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