fix(pwa): remove orientation specifier, respect OS level rotation

Related to #13949

backend/open_webui/main.py

@@ -1776,7 +1776,6 @@ async def get_manifest_json():
             "start_url": "/",
             "display": "standalone",
             "background_color": "#343541",
-            "orientation": "any",
             "icons": [
                 {
                     "src": "/static/logo.png",