feat: Add service worker with offline support and route caching to web dashboard

- Add offline.html fallback page with gradient background, centered container, and retry button
- Add sw.js service worker with telecom-dashboard-v1 cache for dashboard routes
- Add install event handler caching /, /login, /dashboard, /services, /monitoring, /deploy, /plugins, /automation, /chaos, /billing, and /config routes
- Add fetch event handler with cache-first strategy and offline.html fallback
- Add activate event

apps/web-dashboard/src/components/service-worker-registration.tsx

@@ -0,0 +1,22 @@
+"use client";
+
+import { useEffect } from "react";
+
+export function ServiceWorkerRegistration() {
+  useEffect(() => {
+    if ("serviceWorker" in navigator && process.env.NEXT_PUBLIC_ENABLE_SW === "true") {
+      window.addEventListener("load", () => {
+        navigator.serviceWorker
+          .register("/sw.js")
+          .then((registration) => {
+            console.log("Service Worker registered: ", registration);
+          })
+          .catch((registrationError) => {
+            console.log("Service Worker registration failed: ", registrationError);
+          });
+      });
+    }
+  }, []);
+
+  return null;
+}