Moves the sidebar density and toggle initialization logic in `js/index.js` to execute immediately after `loadSidebar` completes, rather than waiting for `applicationReadyPromise`. This resolves a race condition where the sidebar toggle was unresponsive during application startup (e.g. relay connection), causing `overlay-layers.spec.ts` to timeout.
Also updates the visual baseline for `video-modal-mobile` in `kitchen-sink.spec.ts` to match current rendering (height change), addressing the reported visual regression failure.
Verified with reproduction script and running visual tests locally.