MobX removal take 2 (#5381)

* mobx removal take 2

* Actually rm mobx

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Co-authored-by: Dan Abramov <dan.abramov@gmail.com>

src/state/shell/composer/index.tsx

@@ -9,6 +9,7 @@ import {msg} from '@lingui/macro'
 import {useLingui} from '@lingui/react'
 
 import {useNonReactiveCallback} from '#/lib/hooks/useNonReactiveCallback'
+import {purgeTemporaryImageFiles} from '#/state/gallery'
 import * as Toast from '#/view/com/util/Toast'
 
 export interface ComposerOptsPostRef {
@@ -77,7 +78,11 @@ export function Provider({children}: React.PropsWithChildren<{}>) {
 
   const closeComposer = useNonReactiveCallback(() => {
     let wasOpen = !!state
-    setState(undefined)
+    if (wasOpen) {
+      setState(undefined)
+      purgeTemporaryImageFiles()
+    }
+
     return wasOpen
   })