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/DescriptionList.stories.tsx

@@ -0,0 +1,50 @@
+import React from 'react';
+import type { Meta, StoryObj } from '@storybook/react-vite';
+import { DescriptionList } from '../../src/ui/DescriptionList/DescriptionList';
+
+const meta: Meta<typeof DescriptionList> = {
+  title: 'UI/DescriptionList',
+  component: DescriptionList,
+  parameters: { layout: 'centered' },
+  tags: ['autodocs'],
+  decorators: [
+    (Story) => (
+      <div style={{ width: 360 }}>
+        <Story />
+      </div>
+    ),
+  ],
+  argTypes: {
+    layout: { control: 'select', options: ['inline', 'compact'] },
+  },
+};
+export default meta;
+type Story = StoryObj<typeof DescriptionList>;
+
+const urlItems = [
+  { term: 'ID_URL', detail: 'https://id.example.com/' },
+  { term: 'CABINET_URL', detail: 'https://cabinet.example.com/messages' },
+  { term: 'ADMIN_URL', detail: 'https://admin.example.com/' },
+];
+
+export const Inline: Story = {
+  args: { items: urlItems, layout: 'inline' },
+};
+
+export const Compact: Story = {
+  args: { items: urlItems, layout: 'compact' },
+};
+
+export const WithLinks: Story = {
+  args: {
+    layout: 'inline',
+    items: urlItems.map(({ term, detail }) => ({
+      term,
+      detail: (
+        <a href={detail as string} target="_blank" rel="noopener noreferrer">
+          {detail}
+        </a>
+      ),
+    })),
+  },
+};