design: dmarc-day - the reporter's day named as such; confirm's sign-in state

The owner, 2026-10-17: "Показ времени отчёта по UTC принимаем. Это не
проблема. Пояснения добавь. Все мелочи закрой."

A DMARC report's day stays the reporter's, in UTC - the title and the lists
name it - and the panel now says so: the report's Window shows its
boundaries in this panel's zone with a line under them naming the
reporter's day; Settings' Time zone box and Help (#settings, #dmarc) name
it as the one exception to "every time is this zone's".

confirm-email-signin.html: the confirmation link opened without its
account's session (since the security review of password-reset): what to
do, and a link to sign in.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/assets/panel-redesign/panel/src/confirm-email-signin.html

@@ -0,0 +1,18 @@
+<!-- title: Confirm e-mail | shell: bare -->
+<div class="columns is-gapless sp-signin">
+  <div class="column is-half sp-signin-brand">
+    <div>
+      <img src="../../selfpost-stamp.svg" alt="SelfPost">
+      <p>YOUR SMTP. YOUR RULES.</p>
+    </div>
+  </div>
+  <div class="column is-half sp-signin-form">
+    <div class="sp-form">
+      <p class="sp-kicker">mail.example.org</p>
+      <h1 class="title is-3">Confirm e-mail</h1>
+      <div class="notification is-danger is-light"><i class="ti ti-alert-circle"></i>Sign in to the account in this browser, then open the link again.</div>
+      <p><a href="login.html">Sign in</a></p>
+    </div>
+    <p class="sp-foot">Copyright © 2026 Mikhail Yenuchenko · <a href="#">License (AGPL-3.0)</a> · <a href="#">Source</a> · No warranty</p>
+  </div>
+</div>