Fix Mobile PWA not showing in true Fullscreen (#394)

* Fixed Rounding Error For TargetHalfHpDamageAttr

Moves that deal half of a target's HP were not able to deal damage if the target had 1 HP. Used Math.max to ensure 1 is the lowest this value ever evaluates to.

* Fix Mobile PWA not showing in true Fullscreen

adding "fullscreen" to the display attribute wasn't enough, but adding it to the start_url attribute was. This does not appear to affect PC (which is good since it shouldn't).

* 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": "/",
+  "start_url": "https://pokerogue.net",
   "display": "fullscreen",
-  "orientation": "landscape",
   "background_color": "#8c8c8c",
   "theme_color": "#8c8c8c",
   "icons": [