Implementieren der PWA, Multi-Instanzen-Passwort-Schutz und Kassen-Löschfunktion

static/manifest.json

@@ -0,0 +1,21 @@
+{
+  "name": "erdbeerrechner",
+  "short_name": "erdbeer",
+  "description": "Eine anpassbare Kassen-App.",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#f8f9fa",
+  "theme_color": "#dc3545",
+  "icons": [
+    {
+      "src": "/static/icon-192x192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "/static/icon-512x512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    }
+  ]
+}

static/sw.js

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+const CACHE_NAME = 'erdbeerkasse-v1';
+const ASSETS_TO_CACHE = [
+  '/',
+  '/manifest.json',
+  '/static/icon-192x192.png',
+  '/static/icon-512x512.png',
+  'https://maxcdn.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css'
+];
+
+self.addEventListener('install', (event) => {
+  event.waitUntil(
+    caches.open(CACHE_NAME)
+      .then((cache) => cache.addAll(ASSETS_TO_CACHE))
+      .then(() => self.skipWaiting())
+  );
+});
+
+self.addEventListener('activate', (event) => {
+  event.waitUntil(
+    caches.keys().then((cacheNames) => {
+      return Promise.all(
+        cacheNames.map((cacheName) => {
+          if (cacheName !== CACHE_NAME) {
+            return caches.delete(cacheName);
+          }
+        })
+      );
+    })
+  );
+  self.clients.claim();
+});
+
+// Network-first strategy for dynamic instances, fallback to cache
+self.addEventListener('fetch', (event) => {
+  if (event.request.method !== 'GET') {
+    return;
+  }
+  
+  event.respondWith(
+    fetch(event.request)
+      .then((response) => {
+        // Clone the response before caching if it's a valid response
+        if (!response || response.status !== 200 || response.type !== 'basic') {
+          return response;
+        }
+        
+        const responseToCache = response.clone();
+        caches.open(CACHE_NAME).then((cache) => {
+          cache.put(event.request, responseToCache);
+        });
+        
+        return response;
+      })
+      .catch(() => caches.match(event.request))
+  );
+});