feat(dashboard): offline web push — service worker, subscribe flow, deep-link

Notifications phase 2: a /push-sw.js service worker shows a system notification
on push and, on click, focuses an open CRM tab (or opens one) and deep-links to
the thread. usePushNotifications registers the SW, requests permission, subscribes
with IIOS's VAPID key, and stores the subscription via the be-crm door. The topbar
bell becomes a real enable/disable control (hidden when push is unsupported/demo).
Dashboard listens for the SW's notif-click message + a ?thread= deep link.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/dashboard/dashboard.tsx

@@ -39,6 +39,25 @@ export function Dashboard() {
     // eslint-disable-next-line react-hooks/set-state-in-effect
     try { const t = localStorage.getItem("lup_dash_theme"); if (t === "light" || t === "dark") setTheme(t); } catch {}
   }, []);
+
+  // Deep-link from a clicked push notification. Two paths from the service worker:
+  //  - a tab was already open → it postMessages { type: 'notif-click', threadId } to focus here
+  //  - no tab was open → it opens /dashboard?thread=<id>, which we read once on mount
+  useEffect(() => {
+    try {
+      const t = new URLSearchParams(window.location.search).get("thread");
+      if (t) {
+        navigateToConversation("messenger", t);
+        window.history.replaceState({}, "", window.location.pathname);
+      }
+    } catch {}
+    if (!("serviceWorker" in navigator)) return;
+    const onMessage = (e: MessageEvent) => {
+      if (e.data?.type === "notif-click" && e.data.threadId) navigateToConversation("messenger", e.data.threadId);
+    };
+    navigator.serviceWorker.addEventListener("message", onMessage);
+    return () => navigator.serviceWorker.removeEventListener("message", onMessage);
+  }, []);
   function toggle() {
     setTheme((t) => { const n = t === "dark" ? "light" : "dark"; try { localStorage.setItem("lup_dash_theme", n); } catch {} return n; });
   }