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/lessons/sessions/$sessionId.tsx

@@ -18,7 +18,7 @@ import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card'
 import { ArrowLeft, CheckSquare, Square } from 'lucide-react'
 import { toast } from 'sonner'
 import { useAuthStore } from '@/stores/auth.store'
-import type { LessonPlan, LessonPlanSection } from '@/types/lesson'
+import type { LessonPlan, LessonPlanSection, LessonSession } from '@/types/lesson'
 
 export const Route = createFileRoute('/_authenticated/lessons/sessions/$sessionId')({
   component: SessionDetailPage,
@@ -126,7 +126,7 @@ function SessionDetailPage() {
   return (
     <div className="space-y-6 max-w-3xl">
       <div className="flex items-center gap-3">
-        <Button variant="ghost" size="sm" onClick={() => navigate({ to: '/lessons/sessions', search: {} as any })}>
+        <Button variant="ghost" size="sm" onClick={() => navigate({ to: '/lessons/sessions', search: {} as Record<string, unknown> })}>
           <ArrowLeft className="h-4 w-4" />
         </Button>
         <div className="flex-1">
@@ -137,7 +137,7 @@ function SessionDetailPage() {
             <Link
               to="/lessons/enrollments/$enrollmentId"
               params={{ enrollmentId: enrollment.id }}
-              search={{} as any}
+              search={{} as Record<string, unknown>}
               className="text-sm text-primary hover:underline"
             >
               View Enrollment
@@ -209,7 +209,12 @@ function SessionDetailPage() {
 
 // ─── Notes Card ───────────────────────────────────────────────────────────────
 
-function NotesCard({ session, canEdit, onSave, saving }: any) {
+function NotesCard({ session, canEdit, onSave, saving }: {
+  session: LessonSession
+  canEdit: boolean
+  onSave: (data: Record<string, unknown>) => void
+  saving: boolean
+}) {
   const [instructorNotes, setInstructorNotes] = useState(session.instructorNotes ?? '')
   const [memberNotes, setMemberNotes] = useState(session.memberNotes ?? '')
   const [homeworkAssigned, setHomeworkAssigned] = useState(session.homeworkAssigned ?? '')