refactor: update Vault secret paths to new categorized structure

- code-server: code-server → applications/code-server
- mas: mas → applications/mas, postgresql → storage/postgresql
- umami: umami → applications/umami
- headlamp: authelia → security/authelia

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

headlamp/manifests/external-secret.yaml

@@ -23,5 +23,5 @@ spec:
   data:
     - secretKey: clientSecret
       remoteRef:
-        key: authelia
+        key: security/authelia
         property: HEADLAMP_CLIENT_SECRET