feat: add booking management, Open Day, unified signup modal

- MC registrations: notification toggles (confirm/remind) with urgency
- Group bookings: save to DB from BookingModal, admin CRUD at /admin/bookings
- Open Day: full event system with schedule grid (halls × time), per-class
  booking, discount pricing (30 BYN / 20 BYN from 3+), auto-cancel threshold
- Unified SignupModal replaces 3 separate forms — consistent fields
  (name, phone, instagram, telegram), Instagram DM fallback on network error
- Centralized /admin/bookings page with 3 tabs (classes, MC, Open Day),
  collapsible sections, notification toggles, filter chips
- Unread booking badge on sidebar + dashboard widget with per-type breakdown
- Pricing: contact hint (Instagram/Telegram/phone) on price & rental tabs,
  admin toggle to show/hide
- DB migrations 5-7: group_bookings table, open_day tables, unified fields

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/app/admin/pricing/page.tsx

@@ -19,6 +19,7 @@ interface PricingData {
   rentalTitle: string;
   rentalItems: { name: string; price: string; note?: string }[];
   rules: string[];
+  showContactHint?: boolean;
 }
 
 function PriceField({ label, value, onChange }: { label: string; value: string; onChange: (v: string) => void }) {
@@ -63,6 +64,25 @@ export default function PricingEditorPage() {
             onChange={(v) => update({ ...data, subtitle: v })}
           />
 
+          <label className="inline-flex items-center gap-2 cursor-pointer select-none">
+            <button
+              type="button"
+              role="switch"
+              aria-checked={data.showContactHint !== false}
+              onClick={() => update({ ...data, showContactHint: data.showContactHint === false })}
+              className={`relative h-5 w-9 rounded-full transition-colors ${
+                data.showContactHint !== false ? "bg-gold" : "bg-neutral-600"
+              }`}
+            >
+              <span
+                className={`absolute top-0.5 left-0.5 h-4 w-4 rounded-full bg-white transition-transform ${
+                  data.showContactHint !== false ? "translate-x-4" : ""
+                }`}
+              />
+            </button>
+            <span className="text-sm text-neutral-400">Показывать контакты для записи (Instagram, Telegram, телефон)</span>
+          </label>
+
           {/* Featured selector */}
           {(() => {
             const itemOptions = data.items