Added sample page

Not working yet

frontend/src/lib.rs

@@ -1,14 +1,25 @@
-pub fn add(left: u64, right: u64) -> u64 {
-    left + right
-}
+use serde::{Deserialize, Serialize};
+use yew::prelude::*;
 
-#[cfg(test)]
-mod tests {
-    use super::*;
+#[component]
+fn App() -> Html {
+    let counter = use_state(|| 0);
+    let onclick = {
+        let counter = counter.clone();
+        move |_| {
+            let value = *counter + 1;
+            counter.set(value);
+        }
+    };
 
-    #[test]
-    fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
+    html! {
+        <div>
+            <button {onclick}>{ "+1" }</button>
+            <p>{ *counter }</p>
+        </div>
     }
 }
+
+fn main() {
+    yew::Renderer::<App>::new().render();
+}