Allow any orientation for mobile PWA

remove the orientation restriction since it doesn't prevent fullscreen PWA from displaying properly.

public/manifest.webmanifest

@@ -3,9 +3,8 @@
   "short_name": "PokéRogue",
   "description": "A Pokémon fangame heavily inspired by the roguelite genre. Battle endlessly while gathering stacking items, exploring many different biomes, and reaching Pokémon stats you never thought possible.",
   "scope": "/",
-  "start_url": "https://pokerogue.net?fullscreen=true",
+  "start_url": "https://pokerogue.net",
   "display": "fullscreen",
-  "orientation": "landscape",
   "background_color": "#8c8c8c",
   "theme_color": "#8c8c8c",
   "icons": [