homepage: add self-serve account link to authentik user-settings flow

Footer link opens the authentik default-user-settings-flow in a new tab,
giving users a self-service entry point to change their password and
manage MFA/credentials without admin intervention.

shared/homepage/index.html

@@ -18,6 +18,7 @@
   <span>last master deployment: <span id="deployed-at"></span></span>
   <a href="/docs">docs</a>
   <a href="/admin/">admin</a>
+  <a href="https://auth.franksdank.cloud/if/flow/default-user-settings-flow/" target="_blank" rel="noopener">account</a>
 </footer>
 <script src="deployed.js"></script>
 <script src="app.js"></script>