🎨 Palette: [UX improvement] Add tooltip to GitHub link

[JustLookAtNow]

💡 What:

Added a Tooltip widget wrapping the interactive InkWell for the GitHub repository link in the About page.

🎯 Why:

Previously, the GitHub link lacked context when hovering or focusing. This micro-UX improvement clarifies the action ("在浏览器中打开 GitHub 仓库" - Open GitHub repo in browser) before the user clicks it.

📸 Before/After:

No structural changes, but now a standard material tooltip appears when hovering on desktop/web or long-pressing on mobile.

♿ Accessibility:

Provides semantic labeling for screen readers for a custom interactive element (InkWell), following WCAG and Material Design guidelines for interactive icon/text links.

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PR created automatically by Jules for task 4371845682237621832 started by @JustLookAtNow

[google-labs-jules]

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