Add Tippy.js for tooltips in UptimeStatusIsland component and update styles

- Integrated Tippy.js for enhanced tooltip functionality in the UptimeStatusIsland component, providing detailed heartbeat information on hover.
- Added custom styles for Tippy.js tooltips to support light and dark themes.
- Updated package.json and package-lock.json to include @tippyjs/react and its dependencies.

package.json

@@ -29,6 +29,7 @@
     "@astrolib/analytics": "^0.6.1",
     "@astrolib/seo": "^1.0.0-beta.8",
     "@fontsource-variable/inter": "^5.1.1",
+    "@tippyjs/react": "^4.2.6",
     "@types/react": "^19.0.10",
     "@types/react-dom": "^19.0.4",
     "astro": "^5.2.3",