fix(harbor): add secret key names for database and redis passwords

Harbor Helm chart requires both existingSecret and existingSecretKey
parameters to properly reference credentials. Without the key names,
the chart creates secrets with empty passwords, causing authentication
failures between components.

Added:
- database.internal.existingSecretKey: DATABASE_PASSWORD
- redis.internal.existingSecretKey: REDIS_PASSWORD

cluster/platform/harbor/values.yaml

@@ -39,6 +39,7 @@ database:
     # Password from ExternalSecret
     password: ""
     existingSecret: "harbor-credentials"
+    existingSecretKey: "DATABASE_PASSWORD"
     resources:
       requests:
         memory: 1Gi
@@ -62,6 +63,7 @@ redis:
     # Password from ExternalSecret
     jobservicePassword: ""
     existingSecret: "harbor-credentials"
+    existingSecretKey: "REDIS_PASSWORD"
     resources:
       requests:
         memory: 256Mi