panel: make the status page's "Full queue" a button

It was a bare link trailing the queue-summary sentence, while the two
other card actions on the same page (Re-check DNS, Reload configuration)
are buttons. Pull it out of the paragraph and give it the filled button
style through a new a.btn class — the same base rule a.danger already
used, so an action that happens to be a navigation still looks like
every other action.

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

internal/web/static/panel.css

@@ -28,18 +28,20 @@ input {
   border: 1px solid #cfd4da; border-radius: 6px; background: #fff;
 }
 /* One vocabulary for actions. Anything that performs an action looks like a
-   button; an <a> stays a plain link and is only used for navigation. Several
-   actions used to render as bold blue text instead — a POST wrapped in
-   form.inline, a <details> toggle, the delete links — which read as links and
-   left two appearances for the same kind of control. They all get the button
-   look now: filled for a card's own action, and the compact outlined variant
-   further down where actions cluster (table rows, the nav bar). */
-button, a.danger {
+   button: a <button>, or an <a> carrying .btn/.danger where the action is a
+   plain navigation (the delete confirmation page, the full queue view).
+   Several of these used to render as bold blue text instead — a POST wrapped
+   in form.inline, a <details> toggle, the delete links — which read as links
+   and left two appearances for the same kind of control. They all get the
+   button look now: filled for a card's own action, and the compact outlined
+   variant further down where actions cluster (table rows, the nav bar). Bare
+   <a> is left for links that read as part of a sentence or a list. */
+button, a.btn, a.danger {
   display: inline-block; margin-top: 1.2rem; padding: 0.6rem 1.1rem;
   font: inherit; font-size: 1rem; font-weight: 600; text-decoration: none;
   color: #fff; background: #2563eb; border: 0; border-radius: 6px; cursor: pointer;
 }
-button:hover { background: #1d4ed8; }
+button:hover, a.btn:hover { background: #1d4ed8; }
 .error { color: #b42318; margin: 0.6rem 0 0; font-weight: 600; }
 .muted { color: #6b7280; }
 .topbar { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: 1.2rem; }

internal/web/templates/status_body.html

@@ -30,8 +30,8 @@
     {{if .QueueError}}
     <p class="error">{{.QueueError}}</p>
     {{else}}
-    <p>{{if .QueueSummary}}{{.QueueSummary}}{{else}}Mail queue is empty.{{end}}
-    <a href="/queue">Full queue</a></p>
+    <p>{{if .QueueSummary}}{{.QueueSummary}}{{else}}Mail queue is empty.{{end}}</p>
+    <a class="btn" href="/queue">Full queue</a>
     {{end}}
   </div>