feat: centralize popup texts in new admin tab /admin/popups

- New admin page for shared popup texts (success, waiting list, error, Instagram hint)
- Removed popup fields from MC and Open Day admin editors
- All SignupModals now read from centralized popups config
- Stored as "popups" section in DB with fallback defaults

src/lib/db.ts

@@ -519,6 +519,7 @@ const SECTION_KEYS = [
   "schedule",
   "news",
   "contact",
+  "popups",
 ] as const;
 
 export function getSiteContent(): SiteContent | null {
@@ -549,6 +550,12 @@ export function getSiteContent(): SiteContent | null {
     pricing: sections.pricing,
     schedule: sections.schedule,
     news: sections.news ?? { title: "Новости", items: [] },
+    popups: sections.popups ?? {
+      successMessage: "Вы записаны!",
+      waitingListText: "Все места заняты, но мы добавили вас в лист ожидания.\nЕсли кто-то откажется — мы предложим место вам.",
+      errorMessage: "Не удалось отправить заявку. Свяжитесь с нами через Instagram — мы запишем вас!",
+      instagramHint: "По вопросам пишите в Instagram",
+    },
     contact: sections.contact,
     team: {
       title: teamSection.title || "",
@@ -1014,8 +1021,6 @@ export interface OpenDayEvent {
   discountThreshold: number;
   minBookings: number;
   maxParticipants: number;
-  successMessage?: string;
-  waitingListText?: string;
   active: boolean;
 }
 
@@ -1098,8 +1103,6 @@ function mapEventRow(r: OpenDayEventRow): OpenDayEvent {
     discountThreshold: r.discount_threshold,
     minBookings: r.min_bookings,
     maxParticipants: r.max_participants ?? 0,
-    successMessage: r.success_message ?? undefined,
-    waitingListText: r.waiting_list_text ?? undefined,
     active: !!r.active,
   };
 }
@@ -1219,8 +1222,6 @@ export function updateOpenDayEvent(
     discountThreshold: number;
     minBookings: number;
     maxParticipants: number;
-    successMessage: string;
-    waitingListText: string;
     active: boolean;
   }>
 ): void {
@@ -1235,8 +1236,6 @@ export function updateOpenDayEvent(
   if (data.discountThreshold !== undefined) { sets.push("discount_threshold = ?"); vals.push(data.discountThreshold); }
   if (data.minBookings !== undefined) { sets.push("min_bookings = ?"); vals.push(data.minBookings); }
   if (data.maxParticipants !== undefined) { sets.push("max_participants = ?"); vals.push(data.maxParticipants); }
-  if (data.successMessage !== undefined) { sets.push("success_message = ?"); vals.push(data.successMessage || null); }
-  if (data.waitingListText !== undefined) { sets.push("waiting_list_text = ?"); vals.push(data.waitingListText || null); }
   if (data.active !== undefined) { sets.push("active = ?"); vals.push(data.active ? 1 : 0); }
   if (sets.length === 0) return;
   sets.push("updated_at = datetime('now')");