Admin portal (/admin) + free house ads; POL amounts show two decimals

- /admin: email magic-code sign-in allowlisted to ADMIN_EMAIL, 12h admin
  session (cookie iap.adm, persisted in the volume). Bearer ADMIN_PASSWORD
  API access still works. Member area shows an Admin link for that email.
- House ads: admin places banner/text/login/solo/video/featured/visits
  campaigns owned by house@instantadpay.com that cost nothing; budget is
  only a delivery cap, spend is never charged or burned.
- Admin APIs: overview, all campaigns (+pause/resume any), members
  (+re-point sponsor), reports (+resolve), pending burns, rates/site
  config get+patch, creative upload.
- fmtPol rounds to two decimals everywhere (dashboard, toasts, prices).

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

public/my.html

@@ -139,6 +139,7 @@
     <div class="bo-links">
       <span class="bo-cap">Team</span>
       <a href="#" id="chatMenuBtn" class="bo-chat"><svg viewBox="0 0 24 24" width="15" height="15" fill="none" stroke="currentColor" stroke-width="2" style="vertical-align:-2px;margin-right:7px"><path d="M5 5h14a1 1 0 0 1 1 1v9a1 1 0 0 1-1 1H9l-4 4V6a1 1 0 0 1 1-1z"/></svg>Messages<span class="pill" id="chatNavBadge" hidden></span></a>
+      <a href="/admin" id="adminLink" hidden>Admin</a>
     </div>
     <div class="bo-links">
       <span class="bo-cap">Legal</span>
@@ -694,9 +695,9 @@
     </div>
   </div>
 </div>
-<script src="/assets/common.js?v=20260908c"></script>
+<script src="/assets/common.js?v=20260909a"></script>
 <script src="/assets/wallet.js?v=20260908t"></script>
-<script src="/assets/my.js?v=20260908t"></script>
+<script src="/assets/my.js?v=20260909a"></script>
 <script src="/assets/chat.js?v=20260907l"></script>
 </body>
 </html>