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>

umami/manifests/secret.yaml

@@ -14,9 +14,9 @@ spec:
   data:
     - secretKey: database-url
       remoteRef:
-        key: umami
+        key: applications/umami
         property: DATABASE_URL
     - secretKey: hash-salt
       remoteRef:
-        key: umami
+        key: applications/umami
         property: HASH_SALT