[fix](trx-frontend-http): stop doubling the space under the Statistics title

The page titles carry a bottom margin, which is what spaces them from the
content on the plain block panels.  #tab-statistics is not one: it is a
flex column with `gap: 1rem`, so the margin landed on top of that gap and
left 28px under the title where every other page had 12px.

Drop the margin on that panel and let its own gap do the spacing.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GdyUjuXejCEfiub675z6cz
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/trx-frontend-http/assets/web/style.css

@@ -5447,7 +5447,11 @@ body[data-operator-layout="broadcast"] #cw-bar-overlay {
 
 
 /* Page title for destinations reached through the Tools menu.  The tab strip
- * cannot show which of them is active, so each states its own name. */
+ * cannot show which of them is active, so each states its own name.
+ *
+ * The margin is the spacing on the plain block panels; #tab-statistics is a
+ * flex column with its own `gap`, where the margin lands on top of that gap
+ * and doubles the space under the title. */
 .section-heading {
   margin: 0 0 var(--space-3);
   font-size: 1.15rem;
@@ -5455,3 +5459,5 @@ body[data-operator-layout="broadcast"] #cw-bar-overlay {
   line-height: 1.2;
   color: var(--text);
 }
+
+#tab-statistics > .section-heading { margin-bottom: 0; }