fix: use correct envVar format and enable platform services

- Fix envVar field names (key/value/description instead of name/default)
- Ghost: use MariaDB platform service instead of SQLite
- WordPress: use MariaDB platform service
- Nextcloud: use MariaDB + Redis platform services
- Gitea: use MariaDB platform service

apps/wordpress/versions/1.0.0/config.json

@@ -2,21 +2,12 @@
   "image": "wordpress:latest",
   "port": 80,
   "envVars": [
-    {
-      "name": "WORDPRESS_DB_HOST",
-      "required": true
-    },
-    {
-      "name": "WORDPRESS_DB_USER",
-      "default": "wordpress"
-    },
-    {
-      "name": "WORDPRESS_DB_PASSWORD",
-      "required": true
-    },
-    {
-      "name": "WORDPRESS_DB_NAME",
-      "default": "wordpress"
-    }
-  ]
+    { "key": "WORDPRESS_DB_HOST", "value": "${MARIADB_HOST}:${MARIADB_PORT}", "description": "Database host (auto-injected by platform)" },
+    { "key": "WORDPRESS_DB_USER", "value": "${MARIADB_USER}", "description": "Database user (auto-injected by platform)" },
+    { "key": "WORDPRESS_DB_PASSWORD", "value": "${MARIADB_PASSWORD}", "description": "Database password (auto-injected by platform)" },
+    { "key": "WORDPRESS_DB_NAME", "value": "${MARIADB_DATABASE}", "description": "Database name (auto-injected by platform)" }
+  ],
+  "platformRequirements": {
+    "mariadb": true
+  }
 }