🎨 Palette: Improve CategoryRow hit target and accessibility

[acebytes]

💡 What: Wrapped the entire CategoryRow in a Button with a rectangular hit area instead of restricting the clickable region to just the tiny checkbox circle.

🎯 Why: The previous design made it difficult to toggle cache categories because the touch/click target was far too small. Additionally, VoiceOver read every element in the row separately, which was tedious.

📸 Before/After:
(Visual layout remains unchanged due to .buttonStyle(.plain) usage, but the entire row now reacts to taps and cursor clicks.)

♿ Accessibility: Added .accessibilityElement(children: .combine) and an .isSelected trait. Screen readers will now announce the entire row's contents succinctly as a single interactive element and correctly report its toggle state.

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PR created automatically by Jules for task 13602343835282353266 started by @acebytes

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