tower 0.60.2 — Test endpoint derives bucket names from slug

handleTestS3Credentials no longer requires bucket names in YAML —
testTenantS3Buckets derives from slug, same as Save's auto-create.
Test stored creds now works whether the buckets have been created
yet or not. Per-bucket result still surfaces 404 vs 403 vs other.

values.yaml

@@ -9,7 +9,7 @@ backend:
     # so every cluster that runs Tower needs the same imagePullSecret
     # provisioned out-of-band (until cluster-platform-v3 owns it).
     repository: registry.odoosky.cloud/odoosky/docker-mirror/tower
-    tag: "0.60.1"
+    tag: "0.60.2"
     pullPolicy: IfNotPresent
   imagePullSecrets:
     - name: docker-mirror-pull