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/lib/__tests__/realtime.test.ts

@@ -62,7 +62,7 @@ describe('realtime fallback', () => {
     vi.stubGlobal('EventSource', FakeEventSource);
     sessionStorage.clear();
     localStorage.setItem('mindsift_jwt_token', 'test-token');
-    vi.stubGlobal('fetch', vi.fn(async () => new Response('{}', { status: 200 })));
+    vi.stubGlobal('fetch', vi.fn(async () => new Response('{"ticket":"t1"}', { status: 200 })));
   });
   afterEach(() => {
     vi.useRealTimers();
@@ -73,7 +73,7 @@ describe('realtime fallback', () => {
     const api = await loadApi();
     const states: string[] = [];
     api.onRealtimeStatus((connected, transport) => states.push(`${connected}:${transport}`));
-    api.connectWebSocket();
+    await api.connectWebSocket();
     FakeWebSocket.instances[0].open();
     expect(api.getRealtimeTransport()).toBe('ws');
 
@@ -87,9 +87,17 @@ describe('realtime fallback', () => {
     api.disconnectWebSocket();
   });
 
+  it('connects with a one-time ticket, never with the session token in the URL', async () => {
+    const api = await loadApi();
+    await api.connectWebSocket();
+    expect(FakeWebSocket.instances[0].url).toContain('ticket=t1');
+    expect(FakeWebSocket.instances[0].url).not.toContain('test-token');
+    api.disconnectWebSocket();
+  });
+
   it('a WebSocket answering PONG stays in use', async () => {
     const api = await loadApi();
-    api.connectWebSocket();
+    await api.connectWebSocket();
     const ws = FakeWebSocket.instances[0];
     ws.open();
     for (let i = 0; i < 6; i++) {
@@ -104,7 +112,7 @@ describe('realtime fallback', () => {
   it('SSE only counts as connected once the first event arrives', async () => {
     sessionStorage.setItem('mindsift_ws_blocked', 'true');
     const api = await loadApi();
-    api.connectWebSocket();
+    await api.connectWebSocket();
     const es = FakeEventSource.instances[0];
     es.open();
     expect(api.isRealtimeConnected()).toBe(false);
@@ -118,7 +126,7 @@ describe('realtime fallback', () => {
   it('a buffering proxy (stream opens, no events) switches SSE off for this tab', async () => {
     sessionStorage.setItem('mindsift_ws_blocked', 'true');
     const api = await loadApi();
-    api.connectWebSocket();
+    await api.connectWebSocket();
     const es = FakeEventSource.instances[0];
     es.open();
     await vi.advanceTimersByTimeAsync(5_500);