🎨 Palette: Animate and make accessible the App Diagnostics copy action

[emkey1]

💡 What: Added a smooth animation when transitioning the "Copy Report" button state to "Copied" in the App Diagnostics view, along with VoiceOver accessibility announcements.
🎯 Why: The original state change was abrupt visually and completely invisible to screen readers, leaving users with accessibility needs unaware that their action succeeded.
📸 Before/After: Visual jump replaced with a cross-fade transition.
♿ Accessibility: VoiceOver now announces "Copied report" upon success, and the button's accessibilityLabel dynamically updates between "Copy diagnostic report" and "Copied diagnostic report" with an explanatory accessibilityHint.

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PR created automatically by Jules for task 8645914076903737279 started by @emkey1

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