adds install button

src/main/resources/templates/index.html

@@ -4,7 +4,7 @@
     <meta charset="UTF-8">
     <title>Dice-Tower</title>
     <meta name="version" content="{version}">
-
+    <link rel="manifest" href="manifest.json" />
     <link rel="stylesheet" href="/vendor/w3css/4/w3.css">
     <link rel="stylesheet" href="/vendor/font-awesome/css/fontawesome.css">
     <link rel="stylesheet" href="/vendor/font-awesome/css/all.css">
@@ -33,6 +33,17 @@
     if (!localStorage.getItem("userId")) {
         localStorage.setItem("userId", self.crypto.randomUUID());
     }
+    addEventListener("beforeinstallprompt", (event) => {
+        event.preventDefault()
+        let install = document.createElement('button');
+        install.id = 'install'
+        install.style.position = 'absolute'
+        install.style.top = '25px'
+        install.style.right = '25px'
+        install.innerHTML = 'Install Dice-Tower'
+        install.onclick = () => event.prompt()
+        document.body.appendChild(install)
+    });
 </script>
 <div class="w3-container w3-content"
      style="height: 95vh; display: flex; flex-direction: column; justify-content: space-between;  padding: 25px">