Sign-up guard: honeypot field renamed so browser autofill cannot trip it; log every guard rejection; clearer stale-page message

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

public/join.html

@@ -111,7 +111,7 @@
       <h3 id="jnCapH">Join free</h3>
       <p class="muted small" style="margin:0 0 12px" id="jnCapSub">Type your email and we send a 6-digit code. No password, no wallet needed today.</p>
       <p><input id="jnEmail" type="email" placeholder="Your email" autocomplete="email"></p>
-      <input id="jnWebsite" class="hp-field" type="text" name="website" tabindex="-1" autocomplete="off" aria-hidden="true">
+      <input id="jnWebsite" class="hp-field" type="text" name="hp_field_x9" tabindex="-1" autocomplete="off" aria-hidden="true">
       <div id="jnCheck" hidden></div>
       <p id="jnCodeRow" hidden><input id="jnCode" inputmode="numeric" placeholder="6-digit code from your inbox"></p>
       <p id="jnUnder" class="small muted" hidden style="margin:-4px 0 12px"></p>
@@ -155,7 +155,7 @@
     InstantAdPay · <a href="/contract">Contract</a> · <a href="/terms">Terms</a> · <a href="/privacy">Privacy</a> · <a href="/disclaimer">Disclaimer</a>
   </div>
 </div>
-<script src="/assets/common.js?v=20260911b"></script>
+<script src="/assets/common.js?v=20260911c"></script>
 <script src="/assets/join.js?v=20260911a"></script>
 </body>
 </html>