fix: restore accidentally-removed cn import in LabPage and EventsPage

The empty-state migration removed the `cn` import from both files on the
mistaken belief it was unused. In fact each file still uses cn() ~22 times
(ProfileCard, FilterDrawer, event cards, etc.), so /lab and /events crashed
at runtime with "cn is not defined" and hit the route error boundary.
Re-added `import { cn } from '@/lib/utils'` to both.

Co-authored-by: shakespeare.diy <assistant@shakespeare.diy>

src/pages/EventsPage.tsx

@@ -44,6 +44,7 @@ import {
   LayoutGrid,
   CalendarDays,
 } from 'lucide-react';
+import { cn } from '@/lib/utils';
 import { EmptyState as SharedEmptyState, type EmptyStateAction } from '@/components/EmptyState';
 
 // ─── Accent colours ───────────────────────────────────────────────────────────

src/pages/LabPage.tsx

@@ -71,6 +71,7 @@ import {
   PersonStanding,
   ArrowRight,
 } from 'lucide-react';
+import { cn } from '@/lib/utils';
 import { EmptyState as SharedEmptyState } from '@/components/EmptyState';
 import { Avatar, AvatarImage, AvatarFallback } from '@/components/ui/avatar';
 import { ProBadge } from '@/components/ProBadge';