🎨 Palette: Add tooltips to social badges

[google-labs-jules]

💡 What: Added title attributes to the ORCID, Mastodon, and Bluesky social badges in the README.md.
🎯 Why: This provides a helpful tooltip on mouse hover, giving users immediate context about where the link will take them. This creates a more consistent and informative user experience, as other image links in the README already had this behavior.
♿ Accessibility: While the primary accessibility of the image links is handled by the alt text, the title attribute provides a supplementary visual affordance for sighted mouse users.

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PR created automatically by Jules for task 17507978269059117318 started by @Moohan

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