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/contexts/BookingContext.tsx

@@ -0,0 +1,31 @@
+"use client";
+
+import { createContext, useContext, useState, useCallback } from "react";
+
+interface BookingContextValue {
+  bookingOpen: boolean;
+  openBooking: () => void;
+  closeBooking: () => void;
+}
+
+const BookingContext = createContext<BookingContextValue | null>(null);
+
+export function BookingProvider({ children }: { children: React.ReactNode }) {
+  const [bookingOpen, setBookingOpen] = useState(false);
+  const openBooking = useCallback(() => setBookingOpen(true), []);
+  const closeBooking = useCallback(() => setBookingOpen(false), []);
+
+  return (
+    <BookingContext.Provider value={{ bookingOpen, openBooking, closeBooking }}>
+      {children}
+    </BookingContext.Provider>
+  );
+}
+
+const NOOP = () => {};
+const FALLBACK: BookingContextValue = { bookingOpen: false, openBooking: NOOP, closeBooking: NOOP };
+
+/** Returns booking context. Safe to use outside BookingProvider (returns inert fallback). */
+export function useBooking(): BookingContextValue {
+  return useContext(BookingContext) ?? FALLBACK;
+}