feat: add PWA support with service worker and install prompt

public/manifest.json

@@ -0,0 +1,52 @@
+{
+  "name": "Bulwark Webmail",
+  "short_name": "Bulwark",
+  "description": "A modern webmail client built for Stalwart Mail Server",
+  "start_url": "/",
+  "scope": "/",
+  "display": "standalone",
+  "orientation": "portrait-primary",
+  "theme_color": "#ffffff",
+  "background_color": "#ffffff",
+  "icons": [
+    {
+      "src": "/icon-192x192.png",
+      "sizes": "192x192",
+      "type": "image/png",
+      "purpose": "any"
+    },
+    {
+      "src": "/icon-512x512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "any"
+    },
+    {
+      "src": "/icon-192x192.png",
+      "sizes": "192x192",
+      "type": "image/png",
+      "purpose": "maskable"
+    },
+    {
+      "src": "/icon-512x512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "maskable"
+    }
+  ],
+  "categories": ["productivity"],
+  "screenshots": [
+    {
+      "src": "/screenshot-540x720.png",
+      "sizes": "540x720",
+      "type": "image/png",
+      "form_factor": "narrow"
+    },
+    {
+      "src": "/screenshot-1280x720.png",
+      "sizes": "1280x720",
+      "type": "image/png",
+      "form_factor": "wide"
+    }
+  ]
+}

public/sw.js

@@ -0,0 +1,62 @@
+/* eslint-disable no-undef */
+
+const CACHE_NAME = "bulwark-v1";
+const STATIC_ASSETS = ["/", "/manifest.json"];
+
+self.addEventListener("install", (event) => {
+  event.waitUntil(
+    caches.open(CACHE_NAME).then((cache) => {
+      return cache.addAll(STATIC_ASSETS);
+    })
+  );
+  self.skipWaiting();
+});
+
+self.addEventListener("activate", (event) => {
+  event.waitUntil(
+    caches.keys().then((cacheNames) => {
+      return Promise.all(
+        cacheNames
+          .filter((cacheName) => cacheName !== CACHE_NAME)
+          .map((cacheName) => caches.delete(cacheName))
+      );
+    })
+  );
+  self.clients.claim();
+});
+
+self.addEventListener("fetch", (event) => {
+  // Skip non-GET requests
+  if (event.request.method !== "GET") {
+    return;
+  }
+
+  // Skip API requests and external requests
+  if (
+    event.request.url.includes("/api/") ||
+    !event.request.url.startsWith(self.location.origin)
+  ) {
+    return;
+  }
+
+  event.respondWith(
+    caches.match(event.request).then((response) => {
+      if (response) {
+        return response;
+      }
+
+      return fetch(event.request).then((response) => {
+        if (!response || response.status !== 200 || response.type === "error") {
+          return response;
+        }
+
+        const responseToCache = response.clone();
+        caches.open(CACHE_NAME).then((cache) => {
+          cache.put(event.request, responseToCache);
+        });
+
+        return response;
+      });
+    })
+  );
+});