Move /platform/detection vars into /env (#9707)

* Add platform vars to env

* Replace /platform/detection with /env

src/view/com/pager/PagerHeaderContext.tsx

@@ -1,7 +1,7 @@
 import React, {useContext} from 'react'
 import {type SharedValue} from 'react-native-reanimated'
 
-import {isNative} from '#/platform/detection'
+import {IS_NATIVE} from '#/env'
 
 export const PagerHeaderContext = React.createContext<{
   scrollY: SharedValue<number>
@@ -37,7 +37,7 @@ export function PagerHeaderProvider({
 
 export function usePagerHeaderContext() {
   const ctx = useContext(PagerHeaderContext)
-  if (isNative) {
+  if (IS_NATIVE) {
     if (!ctx) {
       throw new Error(
         'usePagerHeaderContext must be used within a HeaderProvider',

src/view/com/pager/PagerWithHeader.tsx

@@ -18,13 +18,13 @@ import Animated, {
 
 import {useNonReactiveCallback} from '#/lib/hooks/useNonReactiveCallback'
 import {ScrollProvider} from '#/lib/ScrollContext'
-import {isIOS} from '#/platform/detection'
 import {
   Pager,
   type PagerRef,
   type RenderTabBarFnProps,
 } from '#/view/com/pager/Pager'
 import {useTheme} from '#/alf'
+import {IS_IOS} from '#/env'
 import {type ListMethods} from '../util/List'
 import {PagerHeaderProvider} from './PagerHeaderContext'
 import {TabBar} from './TabBar'
@@ -273,11 +273,11 @@ let PagerTabBar = ({
   const headerRef = useRef(null)
   return (
     <Animated.View
-      pointerEvents={isIOS ? 'auto' : 'box-none'}
+      pointerEvents={IS_IOS ? 'auto' : 'box-none'}
       style={[styles.tabBarMobile, headerTransform, t.atoms.bg]}>
       <View
         ref={headerRef}
-        pointerEvents={isIOS ? 'auto' : 'box-none'}
+        pointerEvents={IS_IOS ? 'auto' : 'box-none'}
         collapsable={false}>
         {renderHeader?.({setMinimumHeight: setMinimumHeaderHeight})}
         {