Reliably focus keyboard on Android (#4427)

(cherry picked from commit a2d1cf68b9)

src/view/com/composer/Composer.tsx

@@ -134,8 +134,8 @@ export const ComposePost = observer(function ComposePost({
   // See https://github.com/bluesky-social/social-app/pull/4399
   const {setEnabled} = useKeyboardContext()
   React.useEffect(() => {
+    if (!isAndroid) return
     setEnabled(false)
-
     return () => {
       setEnabled(true)
     }
@@ -402,6 +402,37 @@ export const ComposePost = observer(function ComposePost({
     bottomBarAnimatedStyle,
   } = useAnimatedBorders()
 
+  // Backup focus on android, if the keyboard *still* refuses to show
+  useEffect(() => {
+    if (!isAndroid) return
+    if (!isModalReady) return
+
+    function tryFocus() {
+      if (!Keyboard.isVisible()) {
+        textInput.current?.blur()
+        textInput.current?.focus()
+      }
+    }
+
+    tryFocus()
+    // Retry with enough gap to avoid interrupting the previous attempt.
+    // Unfortunately we don't know which attempt will succeed.
+    const retryInterval = setInterval(tryFocus, 500)
+
+    function stopTrying() {
+      clearInterval(retryInterval)
+    }
+
+    // Deactivate this fallback as soon as anything happens.
+    const sub1 = Keyboard.addListener('keyboardDidShow', stopTrying)
+    const sub2 = Keyboard.addListener('keyboardDidHide', stopTrying)
+    return () => {
+      clearInterval(retryInterval)
+      sub1.remove()
+      sub2.remove()
+    }
+  }, [isModalReady])
+
   return (
     <>
       <KeyboardAvoidingView