🎨 Palette: Add ARIA label to Discovery Log close button

[ford442]

💡 What: Added an aria-label="Close discovery log" to the ✕ button inside the Discovery Log overlay.
🎯 Why: The close button only had the text content "✕", which screen readers would read as "times" or similar, making it confusing for non-visual users to understand its purpose. This adds context and improves accessibility.
♿ Accessibility: Ensures WCAG compliance by properly labeling icon-only interactive elements.

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PR created automatically by Jules for task 5281455987180456873 started by @ford442

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