feat: mobile-optimized schedule with compact agenda list view

Mobile shows all days as a vertical timeline with compact class rows
(time + trainer + type on each line). Desktop keeps the card grid.
Filters are horizontally scrollable on mobile.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app/globals.css

@@ -48,3 +48,14 @@ body {
 :focus-visible {
   @apply outline-2 outline-offset-2 outline-[#c9a96e];
 }
+
+/* ===== Scrollbar hide utility ===== */
+
+.scrollbar-hide {
+  -ms-overflow-style: none;
+  scrollbar-width: none;
+}
+
+.scrollbar-hide::-webkit-scrollbar {
+  display: none;
+}