feat: Change game screen and menu class

- Add default option
- Add init and changeView
- Change style to be more specific
- Rename constants and variables

source/style/modules/game/_tfw.scss

@@ -9,12 +9,6 @@
 	display: flex;
 	flex-flow: column nowrap;
 
-	.flex_auto {
-		display: flex;
-		flex: auto;
-		min-height: 0;
-	}
-
 	th,
 	.important,
 	.subtle,
@@ -78,12 +72,18 @@
 		}
 	}
 
-	& > div {
+	.view {
+		flex: auto;
+		display: flex;
 		flex-flow: column nowrap;
+		min-height: 0;
 
 		& > main {
+			flex: auto;
+			display: flex;
 			flex-flow: row nowrap;
 			gap: hippie.$space_double;
+			min-height: 0;
 
 			& > div:last-child {
 				flex: 2;