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/scenario/EditStepPage.tsx

@@ -27,7 +27,7 @@ export function EditStepPage() {
 
   useEffect(() => {
     if (!id || !stepId) return;
-    Promise.all([scenarios.get(Number(id)), steps.get(Number(id), Number(stepId))])
+    Promise.all([scenarios.get(id), steps.get(id, stepId)])
       .then(([sc, st]) => {
         setScenario(sc);
         setStep(st);
@@ -56,7 +56,7 @@ export function EditStepPage() {
     setSaving(true);
     setError(null);
     try {
-      await steps.update(Number(id), Number(stepId), {
+      await steps.update(id!, stepId!, {
         order: Number(order),
         title: title.trim() || undefined,
         type,