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/components/sections/OpenDay.tsx

@@ -204,6 +204,7 @@ function ClassCard({
           onClick={() => {
             window.dispatchEvent(new CustomEvent("openTrainerProfile", { detail: cls.trainer }));
           }}
+          aria-label={`Профиль тренера: ${cls.trainer}`}
           className="relative flex items-center justify-center h-10 w-10 rounded-full overflow-hidden shrink-0 ring-1 ring-white/10 hover:ring-gold/30 transition-all cursor-pointer mt-0.5"
           title={`Подробнее о ${cls.trainer}`}
         >