Aggiunta pagina per appunti condivisi con setup minimale di Preact

_frontend/src/appunti-condivisi.jsx

@@ -0,0 +1,24 @@
+import { render } from 'preact'
+import { useState } from 'preact/hooks'
+
+const Counter = ({}) => {
+    const [value, setValue] = useState(0)
+
+    const increment = () => {
+        setValue(value => value + 1)
+    }
+
+    return (
+        <p>
+            Counter: {value} <button onClick={increment}>+</button>
+        </p>
+    )
+}
+
+render(
+    <>
+        <h1>Preact is Working!</h1>
+        <Counter />
+    </>,
+    document.querySelector('#app')
+)