fix(capa): filter owner dropdown by capa_owner role

Was filtering by non-null department, excluding capa_owner
users who had no department set.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BzvzV91UqHZKM9P58qtvrA

app/(protected)/hse/incidents/[id]/capa/new/page.tsx

@@ -26,7 +26,7 @@ export default async function NewCapaPage({ params }: Props) {
   const { data: users } = await supabase
     .from('users')
     .select('id, name, department')
-    .not('department', 'is', null)
+    .eq('role', 'capa_owner')
     .order('name')
 
   return (