feat: UI improvements — scrollbar, multi-filters, pricing fix, routing, modals

- Global page scrollbar styled with gold theme
- Schedule: multi-select for class types and status tags
- Pricing: fix tab switch blink (display toggle vs conditional render)
- OpenDay: trainer name more prominent, section divider added
- Team: browser back button closes trainer bio (history API)
- Modals: block scroll + compensate scrollbar width to prevent layout shift
- Header: remove booking button from desktop nav

src/app/globals.css

@@ -83,3 +83,27 @@ body {
 .admin-scrollbar::-webkit-scrollbar-thumb:hover {
   background: rgba(255, 255, 255, 0.3);
 }
+
+/* ===== Global page scrollbar ===== */
+
+html {
+  scrollbar-width: thin;
+  scrollbar-color: rgba(201, 169, 110, 0.3) #0a0a0a;
+}
+
+::-webkit-scrollbar {
+  width: 8px;
+}
+
+::-webkit-scrollbar-track {
+  background: #0a0a0a;
+}
+
+::-webkit-scrollbar-thumb {
+  background: rgba(201, 169, 110, 0.3);
+  border-radius: 4px;
+}
+
+::-webkit-scrollbar-thumb:hover {
+  background: rgba(201, 169, 110, 0.5);
+}