Add service worker for push notifications, create calendar layout, and implement WLAN QR code page

- Implemented a service worker (sw.js) to handle push notifications with dynamic options and notification click events.
- Created a calendar layout in test.html with a grid system for displaying events across days and times.
- Developed a visually engaging WLAN QR code page (wlan.html) with animated backgrounds, particle effects, and tips for connecting to the network.

public/sw.js

@@ -0,0 +1,60 @@
+// sw.js
+self.addEventListener("push", function (event) {
+    const data = event.data ? event.data.json() : {};
+
+    const title = data.title || "Shit da ist was falsch"; // title braucht man, sonst Error
+
+    // Dynamisch Options-Objekt nur mit vorhandenen Werten
+    const options = {};
+
+    if (data.body) options.body = data.body;
+    if (data.icon) options.icon = data.icon;
+    if (data.badge) options.badge = data.badge;
+    if (data.actions) options.actions = data.actions;
+    if (data.requireInteraction !== undefined) options.requireInteraction = data.requireInteraction;
+    if (data.renotify !== undefined) options.renotify = data.renotify;
+    if (data.tag) options.tag = data.tag;
+    if (data.vibrate) options.vibrate = data.vibrate;
+    if (data.url) options.data = { url: data.url };
+
+    event.waitUntil(
+        self.registration.showNotification(title, options)
+    );
+});
+
+
+self.addEventListener("notificationclick", function (event) {
+    event.notification.close(); // Notification schließen
+
+    // Prüfen, ob eine Action gedrückt wurde
+    if (event.action) {
+        // Dynamische Aktionen vom Server können hier behandelt werden
+        // Beispiel: Wir öffnen die URL, die im Notification-Data-Feld steht
+        if (event.notification.data && event.notification.data.url) {
+            event.waitUntil(
+                clients.openWindow(event.notification.data.url)
+            );
+        }
+        // Optional: Weitere Action-IDs können hier behandelt werden
+        console.log("Action clicked:", event.action);
+    } else {
+        // Notification selbst angeklickt (ohne Button)
+        if (event.notification.data && event.notification.data.url) {
+            event.waitUntil(
+                clients.openWindow(event.notification.data.url)
+            );
+        }
+    }
+});
+
+self.addEventListener('install', event => {
+    console.log("Service Worker installiert");
+    // Sofort aktivieren, ohne auf alte Version zu warten
+    self.skipWaiting();
+});
+
+self.addEventListener('activate', event => {
+    console.log("Service Worker aktiviert");
+    // Alte Clients übernehmen
+    event.waitUntil(self.clients.claim());
+});