fix(security): stream tickets instead of session tokens in URLs (FLAW-22)

WebSocket and EventSource put the 30-day session token into the URL,
where proxies log it. The app now gets a one-time ticket right before
connecting (POST /auth/stream-ticket, 60 s, bound to the token version);
?token= is no longer accepted for streams, non-browser clients may use
the Authorization header.

With BASE_URL set, CORS allows only that origin and WebSocket upgrades
only it or the requested host; credentials are off (no cookies exist).
Logout, ending all sessions, a new password and deactivation close all
live streams of the account; clients with a valid session reconnect
with a fresh ticket.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/features/lists/SharedListsView.tsx

@@ -11,7 +11,7 @@ import {
   ShoppingCart,
 } from 'lucide-react';
 import { ListItem, SharedList, ListShare, Team, User, WSMessage } from '../../lib/types';
-import { api, buildWebSocketURL, triggerHaptic, createRealtimeConnection, RealtimeTransport } from '../../lib/api';
+import { api, triggerHaptic, createRealtimeConnection, RealtimeTransport } from '../../lib/api';
 import { UnifiedShareModal } from '../../components/UnifiedShareModal';
 import { AvatarStack, AvatarPerson } from '../../components/AvatarStack';
 import { CountBadge } from '../../components/CountBadge';