feat(toolbar): add column visibility and CSV export features

- Implemented GridToolbar component for column visibility and CSV export
- Added ColumnVisibilityMenu for toggling column visibility
- Created exportToCsv function for exporting visible data to CSV
- Updated Griddy component to integrate toolbar functionality
- Enhanced documentation with examples for new features

src/Griddy/features/toolbar/GridToolbar.tsx

@@ -0,0 +1,45 @@
+import type { Table } from '@tanstack/react-table'
+
+import { ActionIcon, Group } from '@mantine/core'
+import { IconDownload } from '@tabler/icons-react'
+
+import { ColumnVisibilityMenu } from '../columnVisibility'
+import { exportToCsv } from '../export'
+
+interface GridToolbarProps<T> {
+  exportFilename?: string
+  showColumnToggle?: boolean
+  showExport?: boolean
+  table: Table<T>
+}
+
+export function GridToolbar<T>({
+  exportFilename = 'export.csv',
+  showColumnToggle = true,
+  showExport = true,
+  table,
+}: GridToolbarProps<T>) {
+  const handleExport = () => {
+    exportToCsv(table, exportFilename)
+  }
+
+  if (!showExport && !showColumnToggle) {
+    return null
+  }
+
+  return (
+    <Group gap="xs" justify="flex-end" p="xs" style={{ borderBottom: '1px solid #e0e0e0' }}>
+      {showExport && (
+        <ActionIcon
+          aria-label="Export to CSV"
+          onClick={handleExport}
+          size="sm"
+          variant="subtle"
+        >
+          <IconDownload size={16} />
+        </ActionIcon>
+      )}
+      {showColumnToggle && <ColumnVisibilityMenu table={table} />}
+    </Group>
+  )
+}