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/lessons/enrollments/index.tsx

@@ -72,7 +72,7 @@ function EnrollmentsListPage() {
   function handleStatusChange(v: string) {
     const s = v === 'all' ? '' : v
     setStatusFilter(s)
-    navigate({ to: '/lessons/enrollments', search: { ...search, status: s || undefined, page: 1 } as Record<string, unknown> })
+    navigate({ to: '/lessons/enrollments', search: { ...search, status: s || undefined, page: 1 } })
   }
 
   return (
@@ -80,7 +80,7 @@ function EnrollmentsListPage() {
       <div className="flex items-center justify-between">
         <h1 className="text-2xl font-bold">Enrollments</h1>
         {hasPermission('lessons.edit') && (
-          <Button onClick={() => navigate({ to: '/lessons/enrollments/new', search: {} as Record<string, unknown> })}>
+          <Button onClick={() => navigate({ to: '/lessons/enrollments/new', search: { page: 1, limit: 25, q: undefined, sort: undefined, order: 'asc' as const } })}>
             <Plus className="mr-2 h-4 w-4" />New Enrollment
           </Button>
         )}
@@ -125,7 +125,7 @@ function EnrollmentsListPage() {
         order={params.order}
         onPageChange={setPage}
         onSort={setSort}
-        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>
   )