chore(footer): remove unverified Bitcoin donation address (#362)

The Bitcoin address that has been listed in the site footer for years
(198uyayMFVHUmrcuzWKFSMAkmwfkQgQEXj) is not verified as belonging to or
being monitored by current maintainers. Leaving a public donation
channel where the destination is unknown is worse than having no
donation channel at all — well-intentioned donors could send funds that
never reach the project.

Removing the listing pending verification of the recipient. If a
verified, monitored donation channel (Bitcoin or otherwise) is set up
in the future, it can be re-added in a dedicated PR alongside any
other supported funding routes.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: JohnMcLear

src/components/Footer.tsx

@@ -17,7 +17,6 @@ export const Footer = ()=>{
                 <p>The Etherpad logos by <span {...CCC_ATTR} property="cc:attributionName">Marcel Klehr</span> are
                     licensed under a <a rel="license" href="https://creativecommons.org/licenses/by-sa/3.0/">Creative
                         Commons Attribution-ShareAlike 3.0 Unported License</a>.</p>
-                <p>Bitcoin public address: 198uyayMFVHUmrcuzWKFSMAkmwfkQgQEXj</p>
                 <p>Thanks to <a href="https://github.com/seballot" target="_blank">@seballot</a> and
                     <a href="https://github.com/SamTV12345" target={"_blank"}> @SamTV12345</a> for the redesign</p>
             </div>