fix: add rel=noopener noreferrer to external links in Footer

[amathxbt]

Bug

The Footer component renders two external links with target="_blank" but no rel attribute:

<a href="https://inkonchain.com/en-US/privacy" target="_blank">
  Privacy Notice
</a>
<a href="https://inkonchain.com/en-US/terms" target="_blank">
  Terms of Service
</a>

Opening a link with target="_blank" without rel="noopener" gives the opened page access to the opener via window.opener. This enables a reverse tabnapping attack where a malicious or compromised destination page can redirect the original tab to a phishing page.

Although modern browsers set rel="noopener" implicitly for cross-origin navigations since Chrome 88 / Firefox 79, the explicit attribute is still required for:

• Older browser support
• Passing security linters and CSP audits
• ESLint rules (jsx-a11y/anchor-is-valid, react/jsx-no-target-blank)

Fix

Add rel="noopener noreferrer" to both links:

<a href="..." target="_blank" rel="noopener noreferrer">

noreferrer additionally prevents the Referer header from leaking the docs URL to the destination.