fix: replace invalid TanStack Router search casts with typed defaults

Newer TanStack Router enforces strict types on search params — 'search: {} as Record<string, unknown>' no longer satisfies routes with validateSearch. Replace all occurrences with the correct search shape for each destination route (pagination defaults for list routes, tab/field defaults for detail routes).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/admin/src/routes/_authenticated/accounts/$accountId/enrollments.tsx

@@ -41,7 +41,7 @@ function AccountEnrollmentsTab() {
       <div className="flex items-center justify-between">
         <p className="text-sm text-muted-foreground">{data?.pagination.total ?? 0} enrollment(s)</p>
         {hasPermission('lessons.edit') && (
-          <Button size="sm" onClick={() => navigate({ to: '/lessons/enrollments/new', search: {} as Record<string, unknown> })}>
+          <Button size="sm" onClick={() => navigate({ to: '/lessons/enrollments/new', search: { page: 1, limit: 25, q: undefined, sort: undefined, order: 'asc' as const } })}>
             <Plus className="h-4 w-4 mr-1" />Enroll a Member
           </Button>
         )}
@@ -55,7 +55,7 @@ function AccountEnrollmentsTab() {
         total={data?.data?.length ?? 0}
         onPageChange={() => {}}
         onSort={() => {}}
-        onRowClick={(e) => navigate({ to: '/lessons/enrollments/$enrollmentId', params: { enrollmentId: e.id }, search: {} as Record<string, unknown> })}
+        onRowClick={(e) => navigate({ to: '/lessons/enrollments/$enrollmentId', params: { enrollmentId: e.id }, search: { page: 1, limit: 25, q: undefined, sort: undefined, order: 'asc' as const } })}
       />
     </div>
   )