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/admin/master-classes/page.tsx

@@ -5,6 +5,7 @@ import Image from "next/image";
 import { SectionEditor } from "../_components/SectionEditor";
 import { InputField, TextareaField, ParticipantLimits, AutocompleteMulti } from "../_components/FormField";
 import { ArrayEditor } from "../_components/ArrayEditor";
+import { PriceField } from "../_components/PriceField";
 import { Plus, X, Upload, Loader2, AlertCircle, Check, Search } from "lucide-react";
 import { adminFetch } from "@/lib/csrf";
 import type { MasterClassItem, MasterClassSlot } from "@/types/content";
@@ -38,32 +39,6 @@ function itemMatchesLocation(item: MasterClassItem, locationFilter: string): boo
   return (item.location || "") === locationFilter;
 }
 
-// --- Price Field ---
-
-function PriceField({ label, value, onChange, placeholder }: { label: string; value: string; onChange: (v: string) => void; placeholder?: string }) {
-  const raw = value.replace(/\s*BYN\s*$/i, "").trim();
-  return (
-    <div>
-      <label className="block text-sm text-neutral-400 mb-1.5">{label}</label>
-      <div className="flex rounded-lg border border-white/10 bg-neutral-800 focus-within:border-gold transition-colors">
-        <input
-          type="text"
-          value={raw}
-          onChange={(e) => {
-            const v = e.target.value;
-            onChange(v ? `${v} BYN` : "");
-          }}
-          placeholder={placeholder ?? "0"}
-          className="flex-1 bg-transparent px-4 py-2.5 text-white placeholder-neutral-500 outline-none min-w-0"
-        />
-        <span className="flex items-center pr-4 text-sm font-medium text-gold select-none">
-          BYN
-        </span>
-      </div>
-    </div>
-  );
-}
-
 interface MasterClassesData {
   title: string;
   items: MasterClassItem[];