feat(settings): Org Settings → Integrations with BYO Twilio SMS

New Settings tab renders an Integrations section; the SMS (Twilio) card lets a
tenant admin connect their own Twilio account (Account SID / write-only Auth Token
/ E.164 from-number) via crm.settings.sms.configure, and shows the masked status
(from-number + SID last-4) from crm.settings.sms.status. Demo mode stores hints
locally. Email (SMTP) shown as the next provider on the same registry.

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

src/components/dashboard/dashboard.tsx

@@ -17,6 +17,7 @@ import { AiAssistant } from "./ai-assistant";
 import { TeamManagement } from "./team-management";
 import { MessengerSdk } from "./messenger-sdk";
 import { InboxSdk } from "./inbox-sdk";
+import { Settings } from "./settings";
 import "../../app/dashboard/dashboard.css";
 
 export function Dashboard() {
@@ -49,6 +50,7 @@ export function Dashboard() {
               : active === "ai" ? <AiAssistant />
               : active === "messenger" ? <MessengerSdk />
               : active === "inbox" ? <InboxSdk />
+              : active === "settings" ? <Settings />
               : active === "team" ? <TeamManagement />
               : <ComingSoon title={title} icon={item?.icon ?? "dashboard"} onGo={setActive} />}
           </ToastProvider>