feat(client): add Card header/footer, DescriptionList, and portal ContextMenu

- add Card header prop (primary/secondary variants) and footer prop (sticks to bottom)
- add Breadcrumbs to all 5 pages; remove duplicate h1 headings
- add pageToolbar layout for breadcrumbs + danger button aligned right
- add DescriptionList component replacing raw dl/dt/dd markup; supports truncate+tooltip
- rewrite ContextMenu to render dropdown via React portal to avoid clip/overflow issues
- update EnvironmentCard to use Card header (primary), footer (Timestamp), and truncated DescriptionList
- fix cog button contrast, square sizing, and right-edge alignment on colored header
- add border to Timestamp pill for dark-mode visibility
- add id badge pill styling to environment card header

client/.storybook/stories/Card.stories.tsx

@@ -18,6 +18,7 @@ const meta: Meta<typeof Card> = {
   ],
   argTypes: {
     padding: { control: 'select', options: ['sm', 'md', 'lg'] },
+    headerVariant: { control: 'select', options: ['primary', 'secondary'] },
   },
 };
 export default meta;
@@ -27,6 +28,31 @@ export const Default: Story = {
   args: { children: 'Card content goes here.', padding: 'md' },
 };
 
+export const WithPrimaryHeader: Story = {
+  args: {
+    header: 'Section Title',
+    headerVariant: 'primary',
+    children: 'Card content with a primary header.',
+  },
+};
+
+export const WithSecondaryHeader: Story = {
+  args: {
+    header: 'Section Title',
+    headerVariant: 'secondary',
+    children: 'Card content with a secondary header.',
+  },
+};
+
+export const WithFooter: Story = {
+  args: {
+    header: 'My Card',
+    headerVariant: 'primary',
+    children: 'Card body content.',
+    footer: 'Last updated 2 minutes ago',
+  },
+};
+
 export const ScenarioCard: Story = {
   render: () => (
     <Card>