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/repair-batches/$batchId.tsx

@@ -96,12 +96,12 @@ function RepairBatchDetailPage() {
   const totalActual = tickets.reduce((sum, t) => sum + (t.actualCost ? parseFloat(t.actualCost) : 0), 0)
 
   function handleTicketClick(ticket: RepairTicket) {
-    navigate({ to: '/repairs/$ticketId', params: { ticketId: ticket.id }, search: {} as any })
+    navigate({ to: '/repairs/$ticketId', params: { ticketId: ticket.id }, search: {} as Record<string, unknown> })
   }
 
   function handleAddRepair() {
     // Navigate to new repair with batch and account pre-linked
-    navigate({ to: '/repairs/new', search: { batchId, batchName: batch!.batchNumber ?? '', accountId: batch!.accountId, contactName: batch!.contactName ?? '' } as any })
+    navigate({ to: '/repairs/new', search: { batchId, batchName: batch!.batchNumber ?? '', accountId: batch!.accountId, contactName: batch!.contactName ?? '' } as Record<string, unknown> })
   }
 
   async function generateBatchPdf() {
@@ -233,7 +233,7 @@ function RepairBatchDetailPage() {
   return (
     <div className="space-y-6 max-w-5xl">
       <div className="flex items-center gap-3">
-        <Button variant="ghost" size="sm" onClick={() => navigate({ to: '/repair-batches', search: {} as any })}>
+        <Button variant="ghost" size="sm" onClick={() => navigate({ to: '/repair-batches', search: {} as Record<string, unknown> })}>
           <ArrowLeft className="h-4 w-4" />
         </Button>
         <div className="flex-1">