refactor: comprehensive frontend review — consistency, a11y, code quality

- Replace event dispatchers with BookingContext (Hero, Header, FloatingContact)
- Add focus trap hook for modals (SignupModal, NewsModal)
- Extract shared components: CollapsibleSection, ConfirmDialog, PriceField, AdminSkeleton
- Add delete confirmation dialog to ArrayEditor
- Replace hardcoded colors (#050505, #0a0a0a, #c9a96e, #2ecc71) with theme tokens
- Add CSS variables --color-surface-deep/dark for consistent dark surfaces
- Improve contrast: muted text neutral-500 → neutral-400 in dark mode
- Fix modal z-index hierarchy (modals z-60, header z-50, floats z-40)
- Consolidate duplicate formatDate → shared formatting.ts
- Add useMemo to TeamProfile groupMap computation
- Fix typography: responsive price text in Pricing section
- Add ARIA labels/expanded to FAQ, OpenDay, ArrayEditor grip handles
- Hide number input spinners globally
- Reorder admin sidebar: Dashboard → SEO → Bookings → site section order
- Use shared PriceField in Open Day editor
- Fix schedule grid first time slot (09:00) clipped by container
- Fix pre-existing type errors (bookings, hero, db interfaces)

src/app/globals.css

@@ -11,6 +11,8 @@
   --color-gold: #c9a96e;
   --color-gold-light: #d4b87a;
   --color-gold-dark: #a08050;
+  --color-surface-deep: #050505;
+  --color-surface-dark: #0a0a0a;
 }
 
 /* ===== Base ===== */
@@ -85,11 +87,23 @@ body {
   background: rgba(255, 255, 255, 0.3);
 }
 
+/* ===== Hide number input spinners ===== */
+
+input[type="number"]::-webkit-inner-spin-button,
+input[type="number"]::-webkit-outer-spin-button {
+  -webkit-appearance: none;
+  margin: 0;
+}
+
+input[type="number"] {
+  -moz-appearance: textfield;
+}
+
 /* ===== Global page scrollbar ===== */
 
 html {
   scrollbar-width: thin;
-  scrollbar-color: rgba(201, 169, 110, 0.3) #0a0a0a;
+  scrollbar-color: rgba(201, 169, 110, 0.3) var(--color-surface-dark);
 }
 
 ::-webkit-scrollbar {
@@ -97,7 +111,7 @@ html {
 }
 
 ::-webkit-scrollbar-track {
-  background: #0a0a0a;
+  background: var(--color-surface-dark);
 }
 
 ::-webkit-scrollbar-thumb {