fix: resolve all frontend lint errors and warnings

Replace all `any` types with proper types across 36 files:
- TanStack Router search params: `{} as Record<string, unknown>`
- API response pagination: proper typed interface
- DataTable column casts: remove unnecessary `as any`
- Function params and event handlers: use specific types
- Remove unused imports and variables in POS components

Frontend lint now passes with 0 errors and 0 warnings.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/admin/src/routes/_authenticated/members/$memberId.tsx

@@ -70,11 +70,11 @@ function statusBadge(status: string) {
   return <Badge variant={variants[status] ?? 'outline'}>{status}</Badge>
 }
 
-const enrollmentColumns: Column<Enrollment>[] = [
+const enrollmentColumns: Column<Enrollment & { instructorName?: string; slotInfo?: string; lessonTypeName?: string }>[] = [
   { key: 'status', header: 'Status', sortable: true, render: (e) => statusBadge(e.status) },
-  { key: 'instructor_name', header: 'Instructor', render: (e) => <>{(e as any).instructorName ?? e.instructorId}</> },
-  { key: 'slot_info', header: 'Day / Time', render: (e) => <>{(e as any).slotInfo ?? '—'}</> },
-  { key: 'lesson_type', header: 'Lesson', render: (e) => <>{(e as any).lessonTypeName ?? '—'}</> },
+  { key: 'instructor_name', header: 'Instructor', render: (e) => <>{e.instructorName ?? e.instructorId}</> },
+  { key: 'slot_info', header: 'Day / Time', render: (e) => <>{e.slotInfo ?? '—'}</> },
+  { key: 'lesson_type', header: 'Lesson', render: (e) => <>{e.lessonTypeName ?? '—'}</> },
   { key: 'start_date', header: 'Start', sortable: true, render: (e) => <>{new Date(e.startDate + 'T00:00:00').toLocaleDateString()}</> },
   { key: 'rate', header: 'Rate', render: (e) => <>{e.rate ? `$${e.rate} / ${e.billingInterval} ${e.billingUnit}` : <span className="text-muted-foreground">—</span>}</> },
 ]
@@ -161,7 +161,7 @@ function MemberDetailPage() {
   })
 
   function setTab(t: string) {
-    navigate({ to: '/members/$memberId', params: { memberId }, search: { tab: t } as any })
+    navigate({ to: '/members/$memberId', params: { memberId }, search: { tab: t } as Record<string, unknown> })
   }
 
   if (isLoading) {
@@ -188,7 +188,7 @@ function MemberDetailPage() {
     <div className="space-y-6">
       {/* Header */}
       <div className="flex items-center gap-3">
-        <Button variant="ghost" size="sm" onClick={() => navigate({ to: '/accounts/$accountId/members', params: { accountId: member.accountId }, search: {} as any })}>
+        <Button variant="ghost" size="sm" onClick={() => navigate({ to: '/accounts/$accountId/members', params: { accountId: member.accountId }, search: {} as Record<string, unknown> })}>
           <ArrowLeft className="h-4 w-4" />
         </Button>
         <div>
@@ -293,7 +293,7 @@ function MemberDetailPage() {
           <div className="flex items-center justify-between">
             <p className="text-sm text-muted-foreground">{enrollmentsData?.pagination.total ?? 0} enrollment(s)</p>
             {hasPermission('lessons.edit') && (
-              <Button size="sm" onClick={() => navigate({ to: '/lessons/enrollments/new', search: { memberId } as any })}>
+              <Button size="sm" onClick={() => navigate({ to: '/lessons/enrollments/new', search: { memberId } as Record<string, unknown> })}>
                 <Plus className="h-4 w-4 mr-1" />Enroll
               </Button>
             )}
@@ -307,7 +307,7 @@ function MemberDetailPage() {
             total={enrollmentsData?.data?.length ?? 0}
             onPageChange={() => {}}
             onSort={() => {}}
-            onRowClick={(e) => navigate({ to: '/lessons/enrollments/$enrollmentId', params: { enrollmentId: e.id }, search: {} as any })}
+            onRowClick={(e) => navigate({ to: '/lessons/enrollments/$enrollmentId', params: { enrollmentId: e.id }, search: {} as Record<string, unknown> })}
           />
         </div>
       )}