beacon: demote sign-in to a low-key topbar link (extension barrier)

Most visitors lack a NIP-07 signer, so a headline 'Sign in with did:nostr'
CTA over-promises. Drop it to a quiet text link until xlogin (extension-free
login) makes the flow smooth enough to re-headline.

Author: melvincarvalho

public/index.html

@@ -114,7 +114,7 @@
   <a class="tb-brand" href="/"><span class="dot"></span> nostr.social</a>
   <nav class="tb-nav">
     <a href="/link">Link your pod</a>
-    <a class="tb-cta" href="https://jss.live/sso/?resolver=https://nostr.social" target="_blank" rel="noopener">Sign in with did:nostr</a>
+    <a href="https://jss.live/sso/?resolver=https://nostr.social" target="_blank" rel="noopener">Sign in</a>
   </nav>
 </header>
 <main>