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/inventory/index.tsx

@@ -71,7 +71,7 @@ function InventoryPage() {
       queryClient.invalidateQueries({ queryKey: productKeys.all })
       toast.success('Product created')
       setCreateOpen(false)
-      navigate({ to: '/inventory/$productId', params: { productId: product.id }, search: {} as any })
+      navigate({ to: '/inventory/$productId', params: { productId: product.id }, search: {} as Record<string, unknown> })
     },
     onError: (err) => toast.error(err.message),
   })
@@ -83,23 +83,23 @@ function InventoryPage() {
 
   function handleCategoryChange(v: string) {
     setCategoryFilter(v === 'all' ? '' : v)
-    navigate({ to: '/inventory', search: { ...search, categoryId: v === 'all' ? undefined : v, page: 1 } as any })
+    navigate({ to: '/inventory', search: { ...search, categoryId: v === 'all' ? undefined : v, page: 1 } as Record<string, unknown> })
   }
 
   function handleActiveChange(v: string) {
     setActiveFilter(v === 'all' ? '' : v)
-    navigate({ to: '/inventory', search: { ...search, isActive: v === 'all' ? undefined : v, page: 1 } as any })
+    navigate({ to: '/inventory', search: { ...search, isActive: v === 'all' ? undefined : v, page: 1 } as Record<string, unknown> })
   }
 
   function handleTypeChange(v: string) {
     setTypeFilter(v === 'all' ? '' : v)
-    navigate({ to: '/inventory', search: { ...search, type: v === 'all' ? undefined : v, page: 1 } as any })
+    navigate({ to: '/inventory', search: { ...search, type: v === 'all' ? undefined : v, page: 1 } as Record<string, unknown> })
   }
 
   function handleLowStockChange(v: string) {
     const on = v === 'true'
     setLowStockFilter(on)
-    navigate({ to: '/inventory', search: { ...search, lowStock: on ? 'true' : undefined, page: 1 } as any })
+    navigate({ to: '/inventory', search: { ...search, lowStock: on ? 'true' : undefined, page: 1 } as Record<string, unknown> })
   }
 
   const columns: Column<Product>[] = [
@@ -246,7 +246,7 @@ function InventoryPage() {
         order={params.order}
         onPageChange={setPage}
         onSort={setSort}
-        onRowClick={(p) => navigate({ to: '/inventory/$productId', params: { productId: p.id }, search: {} as any })}
+        onRowClick={(p) => navigate({ to: '/inventory/$productId', params: { productId: p.id }, search: {} as Record<string, unknown> })}
       />
     </div>
   )