Font tweaks (#5597)

* Increase fontWeight on android

* Use atoms for a couple stray fontWeights

* Rm unused file

src/alf/tokens.ts

@@ -1,6 +1,6 @@
-import {Platform} from 'react-native'
+import {isAndroid} from '#/platform/detection'
 
-export const TRACKING = Platform.OS === 'android' ? 0.1 : 0
+export const TRACKING = isAndroid ? 0.1 : 0
 
 export const color = {
   temp_purple: 'rgb(105 0 255)',
@@ -51,12 +51,9 @@ export const borderRadius = {
  * These correspond to Inter font files we actually load.
  */
 export const fontWeight = {
-  regular: '400',
-  // medium: '500',
-  semibold: '600',
-  // bold: '700',
-  extrabold: '800',
-  // black: '900',
+  normal: '400',
+  bold: isAndroid ? '700' : '600',
+  heavy: isAndroid ? '900' : '800',
 } as const
 
 export const gradients = {