feat: call desk redesign — 2-panel layout, collapsible sidebar, inline AI, ringtone

- Collapsible sidebar with Jotai atom (icon-only mode, persisted to localStorage)
- 2-panel call desk: worklist (60%) + context panel (40%) with AI + Lead 360 tabs
- Inline AI call prep card — known lead summary or unknown caller script
- Active call card with compact Answer/Decline buttons
- Worklist panel with human-readable labels, priority badges, click-to-select
- Context panel auto-switches to Lead 360 when lead selected or call incoming
- Browser ringtone via Web Audio API on incoming calls
- Sonner + Untitled UI IconNotification for toast system
- apiClient pattern: centralized post/get/graphql with auto-toast on errors
- Remove duplicate avatar from top bar, hide floating widget on call desk
- Fix Link routing in collapsed sidebar (was using <a> causing full page reload)
- Fix GraphQL field names: adStatus→status, platformUrl needs subfield selection
- Silent mode for DataProvider queries to prevent toast spam

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/providers/sip-provider.tsx

@@ -55,6 +55,15 @@ export const SipProvider = ({ children }: PropsWithChildren) => {
         setCallStartTime(null);
     }, [callState, setCallDuration, setCallStartTime]);
 
+    // Ringtone on incoming call
+    useEffect(() => {
+        if (callState === 'ringing-in') {
+            import('@/lib/ringtone').then(({ startRingtone }) => startRingtone());
+        } else {
+            import('@/lib/ringtone').then(({ stopRingtone }) => stopRingtone());
+        }
+    }, [callState]);
+
     // Auto-reset to idle after ended/failed
     useEffect(() => {
         if (callState === 'ended' || callState === 'failed') {