panel: align page URLs, titles, and headings

Settings moves to /settings with a 308 redirect from /account; domains, Status, Users, and user forms get matching browser titles and h1 text; backup page title reflects domain import.

Co-Authored-By: Composer <noreply@cursor.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

internal/web/view/templates/domain_detail.html

@@ -53,7 +53,7 @@
   they are policy, and the domain may already publish an SPF record for other
   senders. SelfPost is a send-only relay — most operators have no inbox on the
   sending domain, so the suggested DMARC record omits <code>rua=</code> unless a
-  report address is configured below or in <a href="/account">Settings</a>.
+  report address is configured below or in <a href="/settings">Settings</a>.
   Publish both as TXT records.</p>
 
   <label>SPF — host / name</label>