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/state/sidebar-state.ts

@@ -0,0 +1,11 @@
+import { atom } from 'jotai';
+
+const stored = typeof window !== 'undefined' ? localStorage.getItem('helix_sidebar_collapsed') : null;
+
+export const sidebarCollapsedAtom = atom(
+    stored === 'true',
+    (_get, set, value: boolean) => {
+        set(sidebarCollapsedAtom, value);
+        localStorage.setItem('helix_sidebar_collapsed', String(value));
+    },
+);