fix: Bug - Same user logged in on multiple clients acts like 2 different users

Collapse home and signal-server actor aliases into one canonical room member so multi-device sessions no longer duplicate the local user in the members panel.

Co-authored-by: Cursor <cursoragent@cursor.com>

e2e/tests/auth/multi-device-session.spec.ts

@@ -31,6 +31,14 @@ test.describe('Multi-device session', () => {
       expect(instanceA).not.toEqual(instanceB);
     });
 
+    await test.step('shows one self identity in the members panel on each device', async () => {
+      for (const client of [scenario.clientA, scenario.clientB]) {
+        await expect(
+          membersSidePanel(client.page).getByText(scenario.credentials.displayName, { exact: true })
+        ).toHaveCount(1, { timeout: 20_000 });
+      }
+    });
+
     await test.step('syncs chat from device A to device B', async () => {
       await expectCrossDeviceMessage(scenario.messagesA, scenario.messagesB, messageAtoB);
     });