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/components/pos/pos-register.tsx

@@ -1,5 +1,5 @@
 import { useEffect } from 'react'
-import { useQuery, useQueryClient } from '@tanstack/react-query'
+import { useQuery } from '@tanstack/react-query'
 import { queryOptions } from '@tanstack/react-query'
 import { api } from '@/lib/api-client'
 import { usePOSStore } from '@/stores/pos.store'
@@ -21,8 +21,7 @@ function locationsOptions() {
 }
 
 export function POSRegister() {
-  const { locationId, setLocation, currentTransactionId, drawerSessionId, setDrawerSession } = usePOSStore()
-  const queryClient = useQueryClient()
+  const { locationId, setLocation, currentTransactionId, setDrawerSession } = usePOSStore()
 
   // Fetch locations
   const { data: locationsData } = useQuery(locationsOptions())