init: add source code from src.zip

src/ink/hooks/use-stdin.ts

@@ -0,0 +1,8 @@
+import { useContext } from 'react'
+import StdinContext from '../components/StdinContext.js'
+
+/**
+ * `useStdin` is a React hook, which exposes stdin stream.
+ */
+const useStdin = () => useContext(StdinContext)
+export default useStdin