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/ui/index.ts

@@ -44,3 +44,6 @@ export type { NotificationProps, NotificationVariant } from './Notification/Noti
 
 export { Table } from './Table/Table';
 export type { TableProps, TableColumn } from './Table/Table';
+
+export { UuidBadge } from './UuidBadge/UuidBadge';
+export type { UuidBadgeProps } from './UuidBadge/UuidBadge';