feat: Add WFW-Aushang web app with PWA support, offline caching, and dark mode

- Created index.html for the main application interface with responsive design and dark mode support.
- Added manifest.webmanifest for PWA configuration, including app icons and display settings.
- Implemented service worker (sw.js) for offline caching of assets and network-first strategy for versioning.
- Introduced version.json to manage app versioning.

bibel-pwa/manifest.json

@@ -0,0 +1,21 @@
+{
+  "name": "Bibel Lern‑App",
+  "short_name": "BibelLern",
+  "description": "Lerne Bibeltexte nach Themen und Büchern auswendig mit einem modernen Design.",
+  "start_url": ".",
+  "display": "standalone",
+  "background_color": "#f8f9fa",
+  "theme_color": "#007acc",
+  "icons": [
+    {
+      "src": "icon-192x192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "icon-512x512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    }
+  ]
+}