feat: update lake water data, implement service worker and manifest, and add favicon

public/sw.js

@@ -0,0 +1,66 @@
+const CACHE_NAME = 'hladinator-v1';
+const ASSETS_TO_CACHE = [
+  '/',
+  '/index.html',
+  '/favicon.png',
+  '/manifest.json'
+];
+
+self.addEventListener('install', (event) => {
+  event.waitUntil(
+    caches.open(CACHE_NAME).then((cache) => {
+      return cache.addAll(ASSETS_TO_CACHE);
+    })
+  );
+  self.skipWaiting();
+});
+
+self.addEventListener('activate', (event) => {
+  event.waitUntil(
+    caches.keys().then((keys) => {
+      return Promise.all(
+        keys.map((key) => {
+          if (key !== CACHE_NAME) {
+            return caches.delete(key);
+          }
+        })
+      );
+    })
+  );
+  self.clients.claim();
+});
+
+self.addEventListener('fetch', (event) => {
+  // Only handle same-origin HTTP/HTTPS requests
+  if (!event.request.url.startsWith(self.location.origin)) return;
+
+  event.respondWith(
+    caches.match(event.request).then((cachedResponse) => {
+      if (cachedResponse) {
+        // Fetch new version in background to update cache (stale-while-revalidate)
+        fetch(event.request).then((networkResponse) => {
+          if (networkResponse.status === 200) {
+            caches.open(CACHE_NAME).then((cache) => cache.put(event.request, networkResponse));
+          }
+        }).catch(() => {/* ignore network failures */});
+        
+        return cachedResponse;
+      }
+
+      return fetch(event.request).then((networkResponse) => {
+        // Cache static files and JSON data on the fly
+        if (networkResponse.status === 200 && (
+          event.request.url.includes('.json') || 
+          event.request.url.includes('.css') || 
+          event.request.url.includes('.js')
+        )) {
+          const responseToCache = networkResponse.clone();
+          caches.open(CACHE_NAME).then((cache) => cache.put(event.request, responseToCache));
+        }
+        return networkResponse;
+      }).catch(() => {
+        // Offline fallback
+      });
+    })
+  );
+});