docs: add DMARC report mockups and fold add-domain into lists

Domains and Inbound keep the add field in the list card. The DMARC candidate hub drills into a domain roll-up and a parsed aggregate report, including a third-party fail. The running panel is unchanged.

Co-Authored-By: Cursor <cursoragent@cursor.com>

docs/assets/panel-ui/domain.html

@@ -125,7 +125,7 @@
         </div>
       <label>Value <span class="muted">(from Settings)</span></label>
       <div class="code-row"><span class="code">v=DMARC1; p=none; rua=mailto:dmarc@mail.example.org</span><button type="button" class="copy">Copy</button></div>
-      <p class="muted"><a href="dmarc.html">Open DMARC reports</a> for this domain.</p>
+      <p class="muted"><a href="dmarc-domain.html">Open DMARC reports</a> for this domain.</p>
     </div>
   </div>
   <div class="pair">