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/messenger-sdk.tsx

@@ -37,7 +37,7 @@ function useRealtimeSocket(): MessageSocket | null {
 
 const SHELL = isShellConfigured();
 
-export function MessengerSdk() {
+export function MessengerSdk({ focusThreadId }: { focusThreadId?: string | null } = {}) {
   return (
     <div className="view">
       {!SHELL && (
@@ -55,23 +55,23 @@ export function MessengerSdk() {
           Demo mode — running on the SDK&apos;s mock adapter.
         </div>
       )}
-      <div className="miu-host">{SHELL ? <LiveHost /> : <DemoHost />}</div>
+      <div className="miu-host">{SHELL ? <LiveHost focusThreadId={focusThreadId} /> : <DemoHost focusThreadId={focusThreadId} />}</div>
     </div>
   );
 }
 
 // SHELL is a build-time constant, so exactly one of these mounts for the life of the app
 // (Rules-of-Hooks safe — the other branch never renders).
-function DemoHost() {
+function DemoHost({ focusThreadId }: { focusThreadId?: string | null }) {
   const adapter = useMemo<MessagingAdapter>(() => new MockAdapter(), []);
   return (
     <MessagingProvider adapter={adapter}>
-      <SdkMessenger />
+      <SdkMessenger focusThreadId={focusThreadId} />
     </MessagingProvider>
   );
 }
 
-function LiveHost() {
+function LiveHost({ focusThreadId }: { focusThreadId?: string | null }) {
   const { sdk } = useAppShell();
   const { user } = useAuth();
   const socket = useRealtimeSocket();
@@ -83,7 +83,7 @@ function LiveHost() {
   if (!adapter) return <div className="miu-empty">Loading…</div>;
   return (
     <MessagingProvider adapter={adapter}>
-      <SdkMessenger />
+      <SdkMessenger focusThreadId={focusThreadId} />
     </MessagingProvider>
   );
 }