feat(client): add create/edit environment pages and hoverable cards

- add CreateEnvironmentPage and EditEnvironmentPage with pre-filled form
- add /environments/new and /environments/:id/edit routes
- add Edit option to card context menu and detail page toolbar
- move env id pill to card footer (left), timestamp stays right
- make env cards clickable (navigate to detail); cog stops propagation
- add hoverable Card variant with primary border+shadow on hover
- add link color tokens and global anchor styles for both themes
- fix Timestamp pill visibility in dark mode with border token
- add DescriptionList truncate prop with ellipsis and title tooltip
- stack DescriptionList dd below dt with 8px gap between items

client/src/pages/EnvironmentDetailPage.tsx

@@ -1,7 +1,7 @@
 import { useEffect, useState } from 'react';
 import { useNavigate, useParams } from 'react-router-dom';
 import { useTranslation } from 'react-i18next';
-import { Trash2 } from 'lucide-react';
+import { Pencil, Trash2 } from 'lucide-react';
 import { environments } from '../api';
 import type { Environment } from '../api';
 import { Breadcrumbs, Button, Card, DescriptionList, Timestamp } from '../ui';
@@ -40,10 +40,16 @@ export function EnvironmentDetailPage() {
           ]}
         />
         {env && (
-          <Button variant="danger" size="sm" onClick={handleDelete}>
-            <Trash2 size={14} />
-            {t('environments.action_delete')}
-          </Button>
+          <div className={styles.toolbarActions}>
+            <Button variant="secondary" size="sm" onClick={() => navigate(`/environments/${env.id}/edit`)}>
+              <Pencil size={14} />
+              {t('environments.action_edit')}
+            </Button>
+            <Button variant="danger" size="sm" onClick={handleDelete}>
+              <Trash2 size={14} />
+              {t('environments.action_delete')}
+            </Button>
+          </div>
         )}
       </div>