feat: Remove File Management API from demo specifications

Author: jakubkozera

src/core/demo-dist/demo-info.json

@@ -9,12 +9,6 @@
     "All standard OpenAPI UI features"
   ],
   "sampleSpecs": [
-    {
-      "file": "files.json",
-      "title": "File Management API",
-      "version": "1.0.0",
-      "description": "An API for uploading and downloading files with validation rules."
-    },
     {
       "file": "interactive-api.json",
       "title": "Articles API",
@@ -35,4 +29,4 @@
     }
   ],
   "buildDate": "2025-06-08T12:32:35.312Z"
-}
+}