feat(dss-ui): Button component with design tokens only

- Button.css uses only CSS custom properties, no fallbacks
- Token validator now blocks hardcoded values (strict_mode: true)
- Hook scripts converted from ESM (.js) to CommonJS (.cjs)
- Storybook unified config with HMR disabled for nginx proxy
- Added dss-ui package with Figma-synced components and stories

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

packages/dss-ui/stories/ButtonGroupIconButton.stories.tsx

@@ -0,0 +1,79 @@
+/**
+ * Button Group Icon Button Stories
+ * @generated 2025-12-11T14:37:52.574909
+ */
+import type { Meta, StoryObj } from '@storybook/preact';
+import { ButtonGroupIconButton, type ButtonGroupIconButtonProps } from '../src/atoms/ButtonGroupIconButton';
+
+const meta: Meta<ButtonGroupIconButtonProps> = {
+  title: '2. Atoms/ButtonGroupIconButton',
+  component: ButtonGroupIconButton,
+  tags: ['autodocs'],
+  parameters: {
+    docs: {
+      description: {
+        component: `Auto-generated ButtonGroupIconButton component
+
+**Classification:** atom
+**Slots:** icon
+**Figma ID:** 784:87178`
+      }
+    }
+  },
+  argTypes: {
+    skin: {
+      control: 'select',
+      options: ['Ghost', 'Outlined'],
+      description: 'Skin variant',
+    },
+    size: {
+      control: 'select',
+      options: ['Default', 'Large', 'Small'],
+      description: 'Size variant',
+    },
+    position: {
+      control: 'select',
+      options: ['Left', 'Middle', 'Right', 'Single'],
+      description: 'Position variant',
+    },
+    state: {
+      control: 'select',
+      options: ['Default', 'Disabled', 'Focus', 'Hover'],
+      description: 'State variant',
+    },
+  },
+};
+
+export default meta;
+type Story = StoryObj<ButtonGroupIconButtonProps>;
+
+export const Default: Story = {
+  args: {
+    skin: 'Ghost',
+    size: 'Default',
+    position: 'Left',
+    state: 'Default',
+    children: 'ButtonGroupIconButton'
+  },
+};
+
+export const SizeDefault: Story = {
+  args: {
+    ...Default.args,
+    size: 'Default',
+  },
+};
+
+export const SizeLarge: Story = {
+  args: {
+    ...Default.args,
+    size: 'Large',
+  },
+};
+
+export const SizeSmall: Story = {
+  args: {
+    ...Default.args,
+    size: 'Small',
+  },
+};