feat: Add PWA support with service worker and caching

- Implemented service worker registration in main.js
- Added icons for PWA in manifest.json
- Created a basic service worker (sw.js) for caching static assets
- Generated a list of files to cache using a Node.js script (generate-pwa-cache-list.js)
- Added icon images (icon-192.png and icon-512.png) for PWA
- Defined PWA manifest with app details and icon references

public/sw.js

@@ -0,0 +1,54 @@
+// Basic service worker for caching static assets
+// List of all files in the public folder to cache
+const CACHE_NAME = 'pwa-cache-v5';
+
+self.addEventListener('install', event => {
+  event.waitUntil(
+    fetch('/pwa-files-to-cache.json')
+      .then(response => response.json())
+      .then(files => {
+        return caches.open(CACHE_NAME).then(cache => {
+          return cache.addAll(files);
+        });
+      })
+      .catch(err => {
+        console.error('Failed to fetch pwa-files-to-cache.json', err);
+      })
+  );
+  self.skipWaiting();
+});
+
+self.addEventListener('activate', event => {
+  event.waitUntil(
+    caches.keys().then(cacheNames => {
+      return Promise.all(
+        cacheNames.filter(name => name !== CACHE_NAME).map(name => caches.delete(name))
+      );
+    })
+  );
+  self.clients.claim();
+});
+
+self.addEventListener('fetch', event => {
+  if (event.request.method !== 'GET') return;
+  const url = new URL(event.request.url);
+  // Remove query params for cache matching for static files
+  let cacheKey = url.pathname;
+  // Only do this for files we know are static (e.g., /data/, /logos/, /logos_gen/, /public/)
+  if (cacheKey.startsWith('/data/') || cacheKey.startsWith('/logos/') || cacheKey.startsWith('/logos_gen/')) {
+    // ignore query params
+  } else {
+    cacheKey = event.request.url;
+  }
+  event.respondWith(
+    caches.match(cacheKey).then(response => {
+      if (response) return response;
+      return fetch(event.request).catch(() => {
+        if (event.request.mode === 'navigate') {
+          return caches.match('/index.html');
+        }
+        return Response.error();
+      });
+    })
+  );
+});