Add dismissible Weekly Huddle pop-up overlay (Sept 8)

Self-contained /announce.js injects a branded, dismissible event overlay
(the flyer + all four time zones + Join Google Meet button). Included on the
main funnel and member pages. Auto-expires after the huddle and shows once
per browser until dismissed; edit the EV block to reuse for future events.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

public/fast-start.html

@@ -112,4 +112,5 @@
 <script src="/qrlib.js"></script>
 <script src="/fast-start.js"></script>
 <script src="/chat.js" defer></script>
-<script src="/translate.js" defer></script><script src="/tg-app.js" defer></script></body></html>
+<script src="/translate.js" defer></script><script src="/tg-app.js" defer></script>  <script src="/announce.js"></script>
+</body></html>