feat: dynamic SIP from agentConfig, logout cleanup, heartbeat

- SIP provider reads credentials from agentConfig (login response)
- Auth logout calls sidecar to unlock Redis + Ozonetel logout
- AppShell heartbeat every 5 min for CC agents
- Login stores agentConfig in localStorage

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

src/components/layout/app-shell.tsx

@@ -1,4 +1,4 @@
-import type { ReactNode } from 'react';
+import { useEffect, type ReactNode } from 'react';
 import { useLocation } from 'react-router';
 import { Sidebar } from './sidebar';
 import { SipProvider } from '@/providers/sip-provider';
@@ -13,6 +13,25 @@ export const AppShell = ({ children }: AppShellProps) => {
     const { pathname } = useLocation();
     const { isCCAgent } = useAuth();
 
+    // Heartbeat: keep agent session alive in Redis (CC agents only)
+    useEffect(() => {
+        if (!isCCAgent) return;
+
+        const beat = () => {
+            const token = localStorage.getItem('helix_access_token');
+            if (token) {
+                const apiUrl = import.meta.env.VITE_API_URL ?? 'http://localhost:4100';
+                fetch(`${apiUrl}/auth/heartbeat`, {
+                    method: 'POST',
+                    headers: { Authorization: `Bearer ${token}` },
+                }).catch(() => {});
+            }
+        };
+
+        const interval = setInterval(beat, 5 * 60 * 1000);
+        return () => clearInterval(interval);
+    }, [isCCAgent]);
+
     return (
         <SipProvider>
             <div className="flex h-screen bg-primary">