fix: Implement Network-First SW strategy, no-cache headers in Nginx for index.html/sw.js, and auto 401 token cleanup to fix post-redeploy stale cache issues

frontend/public/sw.js

@@ -1,16 +1,6 @@
-const CACHE_NAME = 'schichtplaner-v1';
-const ASSETS_TO_CACHE = [
-  '/',
-  '/index.html',
-  '/manifest.json'
-];
+const CACHE_NAME = 'schichtplaner-v2';
 
 self.addEventListener('install', (event) => {
-  event.waitUntil(
-    caches.open(CACHE_NAME).then((cache) => {
-      return cache.addAll(ASSETS_TO_CACHE);
-    })
-  );
   self.skipWaiting();
 });
 
@@ -18,29 +8,36 @@ self.addEventListener('activate', (event) => {
   event.waitUntil(
     caches.keys().then((keys) => {
       return Promise.all(
-        keys.map((key) => {
-          if (key !== CACHE_NAME) {
-            return caches.delete(key);
-          }
-        })
+        keys.map((key) => caches.delete(key))
       );
-    })
+    }).then(() => self.clients.claim())
   );
-  self.clients.claim();
 });
 
+// Network-First Strategy for fresh deployments
 self.addEventListener('fetch', (event) => {
   if (event.request.method !== 'GET' || event.request.url.includes('/api/')) {
     return;
   }
+
   event.respondWith(
-    caches.match(event.request).then((cachedResponse) => {
-      if (cachedResponse) {
-        return cachedResponse;
-      }
-      return fetch(event.request).catch(() => {
-        return caches.match('/index.html');
-      });
-    })
+    fetch(event.request)
+      .then((networkResponse) => {
+        if (networkResponse && networkResponse.status === 200 && networkResponse.type === 'basic') {
+          const responseToCache = networkResponse.clone();
+          caches.open(CACHE_NAME).then((cache) => {
+            cache.put(event.request, responseToCache);
+          });
+        }
+        return networkResponse;
+      })
+      .catch(() => {
+        return caches.match(event.request).then((cachedResponse) => {
+          if (cachedResponse) return cachedResponse;
+          if (event.request.mode === 'navigate') {
+            return caches.match('/index.html');
+          }
+        });
+      })
   );
 });