feat(export-import): add yaml export/import with id upsert for credentials, snippets, and scenarios

- all entities export a kind field (credential/snippet/scenario) for safe type checking on import
- import upserts by id: overwrites if id exists, creates with explicit id otherwise
- scenario export now includes id and step ids; import deletes old steps before recreating
- add GET /:id/export and POST /import endpoints to credential and snippet controllers
- add UuidBadge ui component: shortens uuid to first+last 4 hex chars, tooltip, clipboard copy with animated ClipboardCheck icon pop
- apply UuidBadge across all entity id display sites (detail pages, card footers, table columns)
- add export/import buttons to CredentialsPage, SnippetsPage, CredentialDetailPage, SnippetDetailPage

client/src/pages/run/AllRunsPage.tsx

@@ -3,7 +3,7 @@ import { useNavigate } from 'react-router-dom';
 import { useTranslation } from 'react-i18next';
 import { runs } from '../../api';
 import type { ScenarioRun, ScenarioRunStep, ScenarioRunStatus } from '../../api';
-import { AutoRefreshIndicator, Badge, Table, Timestamp, type TableColumn } from '../../ui';
+import { AutoRefreshIndicator, Badge, Table, Timestamp, UuidBadge, type TableColumn } from '../../ui';
 import type { BadgeVariant } from '../../ui';
 import styles from '../Page.module.css';
 
@@ -57,7 +57,7 @@ export function AllRunsPage() {
   }, []);
 
   const columns: TableColumn<AllRunRow>[] = [
-    { key: 'id', header: t('runs.col_id'), render: (r) => r.id, width: 60 },
+    { key: 'id', header: t('runs.col_id'), render: (r) => <UuidBadge id={r.id} />, width: 60 },
     {
       key: 'scenario',
       header: t('runs.col_scenario'),