Traffic Desk: stop-and-refund, plus never let a banner dead-end

Three fixes from live testing of the Traffic Desk:

- /p/<id> with no page built now 302s to /join/<id> instead of returning
  raw JSON 404. Any /p/ link already on a banner, flyer, or in a DM must
  always land somewhere useful.
- The personal-page ad destination is only offered (client) and only
  accepted (server) once a page actually exists; otherwise the member is
  pointed at the Page Builder.
- Members can stop a running banner and get the unserved impressions back
  in their monthly balance. Counters are read before deactivation, since
  deactivating zeroes `remaining` and would look fully served.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

public/suite-traffic.html

@@ -69,7 +69,7 @@
 
   <div class="tf-live" id="tfLiveWrap" style="display:none">
     <h2 style="font-size:20px;margin:0 0 8px">Your running banners</h2>
-    <div class="table-wrap"><table><thead><tr><th>Size</th><th>Sends to</th><th>Bought</th><th>Served</th><th>Left</th><th>Clicks</th><th>Status</th></tr></thead><tbody id="tfLive"></tbody></table></div>
+    <div class="table-wrap"><table><thead><tr><th>Size</th><th>Sends to</th><th>Bought</th><th>Served</th><th>Left</th><th>Clicks</th><th>Status</th><th></th></tr></thead><tbody id="tfLive"></tbody></table></div>
   </div>
 
   <p class="tf-note"><strong style="color:var(--text)">What this is, honestly:</strong> display advertising is <strong style="color:var(--text)">awareness volume</strong> — it puts your link in front of people browsing the network. It is not a lead list, and click rates on display inventory are low by nature. The conversations you have with people you know are still what actually builds a team; this runs quietly in the background while you do that. <br><br>All banners use approved team creative, so every ad on the network stays on-brand. Independent team resource · No income is guaranteed · Cryptocurrency involves risk.</p>