🔒 Fix reverse tabnabbing vulnerability in social.html

[hodovani]

🎯 What: Fixed a reverse tabnabbing vulnerability in _includes/social.html by appending noopener noreferrer to the rel attribute of social media anchor links that use target="_blank".

⚠️ Risk: Without noopener noreferrer, when a user clicked a social media link and it opened in a new tab, the newly opened page would have access to the window.opener object. This object could have been used by a malicious page (or an untrusted script on the target page) to maliciously redirect the user's original referring tab, which is a reverse tabnabbing risk.

🛡️ Solution: Added noopener noreferrer to the rel attribute of the affected anchor tags, safely preserving the original rel="me". I also scanned the repository using grep for other occurrences of target="_blank" and found _includes/share.html, but it already correctly included rel="noopener noreferrer". Tests and site builds were confirmed to pass locally.

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PR created automatically by Jules for task 18147369036786890761 started by @hodovani

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