feat(search): global conversation search in the topbar with deep-link nav

Topbar search box → debounced crm.search → dropdown of hits (chat/mail, highlighted
snippet). Clicking a hit switches to the right tab and focuses the exact thread:
mail → Inbox, chat → Messenger (via the SDK's new focusThreadId, 0.1.6). Snippet HTML
is escaped except the <em> highlight. Demo mode searches an in-memory set.

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

src/components/dashboard/topbar.tsx

@@ -5,13 +5,14 @@ import { useRouter } from "next/navigation";
 import { Sun, Moon, ChevronDown, LogOut } from "lucide-react";
 import { useAuth } from "@abe-kap/appshell-sdk/react";
 import { Icon } from "./ui";
+import { GlobalSearch } from "./global-search";
 import { user } from "./account-data";
 
 function initialsOf(name: string): string {
   return name.split(/\s+/).filter(Boolean).slice(0, 2).map((p) => p[0]).join("").toUpperCase() || "?";
 }
 
-export function Topbar({ theme, onToggle, title, subtitle }: { theme: "dark" | "light"; onToggle: () => void; title: string; subtitle: string }) {
+export function Topbar({ theme, onToggle, title, subtitle, onNavigate }: { theme: "dark" | "light"; onToggle: () => void; title: string; subtitle: string; onNavigate: (surface: "messenger" | "inbox", threadId: string) => void }) {
   // When signed in through the Shell, show the real identity from the App Context
   // Envelope; otherwise fall back to the static demo user.
   const router = useRouter();
@@ -35,7 +36,7 @@ export function Topbar({ theme, onToggle, title, subtitle }: { theme: "dark" | "
         <p>{subtitle}</p>
       </div>
       <div className="top-actions">
-        <button className="ic-btn" aria-label="Search"><Icon name="search" size={18} /></button>
+        <GlobalSearch onNavigate={onNavigate} />
         <button className="ic-btn" aria-label="Toggle theme" onClick={onToggle}>
           {theme === "dark" ? <Moon size={18} /> : <Sun size={18} />}
         </button>