Fix progress bars not clearing on completion after React 19 upgrade

The Ink 6 / React 19 upgrade (269f3aa) deferred unmountInk() in
ConcurrentOutput to let React 19 flush batched state updates, but
missed the same pattern in useAsyncAndUnmount (used by Tasks) and
SingleTask. Without the deferral, unmountInk() fires before the
setState that triggers `return null` is flushed, so the final render
still contains the LoadingBar and it is never erased.

Wrap unmountInk() in setImmediate() in both places, matching the
existing fix in ConcurrentOutput.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: nickwesselman

packages/cli-kit/src/private/node/ui/components/SingleTask.tsx

@@ -35,11 +35,13 @@ const SingleTask = <T,>({task, title, onComplete, onAbort, noColor}: SingleTaskP
       .then((result) => {
         setIsDone(true)
         onComplete?.(result)
-        unmountInk()
+        // Defer unmount so React 19 can flush batched state updates
+        // before the component tree is torn down.
+        setImmediate(() => unmountInk())
       })
       .catch((error) => {
         setIsDone(true)
-        unmountInk(error)
+        setImmediate(() => unmountInk(error))
       })
   }, [task, unmountInk, onComplete])
 

packages/cli-kit/src/private/node/ui/hooks/use-async-and-unmount.ts

@@ -16,11 +16,13 @@ export default function useAsyncAndUnmount(
     asyncFunction()
       .then(() => {
         onFulfilled()
-        unmountInk()
+        // Defer unmount so React 19 can flush batched state updates
+        // before the component tree is torn down.
+        setImmediate(() => unmountInk())
       })
       .catch((error) => {
         onRejected(error)
-        unmountInk(error)
+        setImmediate(() => unmountInk(error))
       })
   }, [])
 }