fix: implement S3 listBuckets to actually list buckets

- Add @aws-sdk/client-s3 dependency for direct S3 operations
- Fix listBuckets handler which was hardcoded to return empty array
- Now properly queries S3 and returns actual bucket names

pnpm-lock.yaml

@@ -17,6 +17,9 @@ importers:
       '@api.global/typedserver':
         specifier: ^8.3.0
         version: 8.3.0(@tiptap/pm@2.27.2)
+      '@aws-sdk/client-s3':
+        specifier: ^3.975.0
+        version: 3.975.0
       '@design.estate/dees-catalog':
         specifier: ^3.37.0
         version: 3.37.0(@tiptap/pm@2.27.2)