feat: added PWA support

static/sw.js

@@ -0,0 +1,62 @@
+const CACHE_NAME = 'votify-v1';
+const APP_SHELL = [
+    '/',
+    '/static/favicon.ico',
+    '/static/manifest.json',
+    '/static/icons/icon-192x192.png',
+    '/static/icons/icon-512x512.png',
+    '/offline',
+];
+
+self.addEventListener('install', (event) => {
+    event.waitUntil(
+        caches.open(CACHE_NAME)
+            .then(cache => cache.addAll(APP_SHELL))
+            .then(() => self.skipWaiting())
+    );
+});
+
+self.addEventListener('activate', (event) => {
+    event.waitUntil(
+        caches.keys().then(keys =>
+            Promise.all(keys.filter(k => k !== CACHE_NAME).map(k => caches.delete(k)))
+        ).then(() => self.clients.claim())
+    );
+});
+
+self.addEventListener('fetch', (event) => {
+    const url = new URL(event.request.url);
+
+    // API calls: network only
+    if (url.pathname.startsWith('/api/')) {
+        return;
+    }
+
+    // Navigation requests: network first, cache fallback, then offline page
+    if (event.request.mode === 'navigate') {
+        event.respondWith(
+            fetch(event.request)
+                .then(response => {
+                    const clone = response.clone();
+                    caches.open(CACHE_NAME).then(cache => cache.put(event.request, clone));
+                    return response;
+                })
+                .catch(() => caches.match(event.request).then(r => r || caches.match('/offline')))
+        );
+        return;
+    }
+
+    // Static assets: cache first, network fallback
+    if (url.pathname.startsWith('/static/')) {
+        event.respondWith(
+            caches.match(event.request).then(cached =>
+                cached || fetch(event.request).then(response => {
+                    const clone = response.clone();
+                    caches.open(CACHE_NAME).then(cache => cache.put(event.request, clone));
+                    return response;
+                })
+            )
+        );
+        return;
+    }
+});