test(web): restore main's right-panel migration expectations after the panel-visibility merge

The keep-both merge nested main's plan-surface migration test inside a
branch popover test and dropped the threadPanelVisibilityByThreadKey key
from the migration results. Restore main's test body and include the
branch's (empty) visibility map in the expected persisted shape.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
bc807fc7d9Julius Marminge committed on 8/29/2026, 6:02:17 AMparent605a8da
2 files changedLine totals unavailable