feat: add dropdown component

inertia/components/common/dropdown/dropdown_item.tsx

@@ -0,0 +1,16 @@
+import styled from '@emotion/styled';
+
+const DropdownItem = styled.div(({ theme }) => ({
+  fontSize: '14px',
+  padding: '8px 12px',
+  display: 'flex',
+  gap: '0.35em',
+  alignItems: 'center',
+  borderRadius: theme.border.radius,
+
+  '&:hover': {
+    backgroundColor: theme.colors.background,
+  },
+}));
+
+export default DropdownItem;