fix(events): server-side search/pagination to remove first-100 cap (#346)

Counters and search on Admin → Events were bounded to the first 100 rows
returned from /admin/events?page=1&limit=100, so on instances with more
events the totals were wrong and search couldn't find anything outside
that window. The dashboard's expiring list had the same first-100 issue.

Backend
- adminEvents.js: extend search to include customer_email so the column
  shown in the table is actually queryable.
- adminDashboard.js: add totalEvents to /dashboard/stats so the events
  page can render an accurate "All (N)" / Total Events counter without
  walking the full table on the client.

Frontend
- events.service.ts: getEvents() now accepts search + the full status
  enum (active|inactive|archived|draft|expiring); response type matches
  the actual {events, pagination} shape.
- admin.service.ts: DashboardStats gains totalEvents.
- EventsListPage.tsx: rewired around server-side pagination, status
  filter, and 300ms-debounced search; Prev/Next + range/page indicator
  below the table; placeholderData keeps the previous page visible
  during fetches; stat cards and "All (N)" pull from /dashboard/stats so
  totals stay accurate regardless of the visible page; archive/delete
  invalidates dashboard-stats so cards refresh.
- AdminDashboard.tsx: expiring list now fetches getEvents(1, 5,
  'expiring') directly instead of slicing the first 100 client-side. As
  a side effect the dashboard's "expiring" definition now matches the
  backend (was excluding events expiring within the next 24h).

frontend/src/services/admin.service.ts

@@ -10,6 +10,7 @@ export interface DashboardStats {
   viewsTrend: number;
   downloadsTrend: number;
   archivedEvents: number;
+  totalEvents: number;
 }
 
 export interface SystemHealth {

frontend/src/services/events.service.ts

@@ -64,11 +64,16 @@ interface UpdateEventData {
   default_photo_sort?: string;
 }
 
+export type EventStatusFilter = 'active' | 'inactive' | 'archived' | 'draft' | 'expiring';
+
 interface EventsListResponse {
   events: Event[];
-  total: number;
-  page: number;
-  limit: number;
+  pagination: {
+    page: number;
+    limit: number;
+    total: number;
+    totalPages: number;
+  };
 }
 
 export const eventsService = {
@@ -76,16 +81,20 @@ export const eventsService = {
   async getEvents(
     page: number = 1,
     limit: number = 20,
-    status?: 'active' | 'inactive' | 'archived' | 'draft'
+    status?: EventStatusFilter,
+    search?: string
   ): Promise<EventsListResponse> {
     const params = new URLSearchParams({
       page: page.toString(),
       limit: limit.toString(),
     });
-    
+
     if (status) {
       params.append('status', status);
     }
+    if (search) {
+      params.append('search', search);
+    }
 
     const response = await api.get<EventsListResponse>(`/admin/events?${params}`);
     const data: any = response.data;