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/repairs/$ticketId.tsx

@@ -175,7 +175,7 @@ function RepairTicketDetailPage() {
     <div className="space-y-4 max-w-5xl">
       {/* Header */}
       <div className="flex items-center gap-3">
-        <Button variant="ghost" size="sm" onClick={() => navigate({ to: '/repairs', search: {} as any })}>
+        <Button variant="ghost" size="sm" onClick={() => navigate({ to: '/repairs', search: {} as Record<string, unknown> })}>
           <ArrowLeft className="h-4 w-4" />
         </Button>
         <div className="flex-1">