feat(nav): add grouped navigation with classic fallback (#1801)

* feat(nav): add grouped navigation with classic fallback

Persist the navigation layout through typed settings, normalize the shared screen selection, and show a versioned migration notice. Preserve the existing Classic user-visible screens while the grouped redesign is delivered incrementally.

* fix(settings): version navigation announcement state

Use a monotonic numeric acknowledgement version across Rust settings, generated bindings, frontend state, and E2E fixtures so future announcements do not overwrite newer acknowledgement state.

* fix(nav): preserve display selection during startup

Gate layout-specific display normalization until settings have loaded so Classic selections are never overwritten by the grouped default. Serialize announcement metadata from Rust, prevent overlapping navigation mutations, and make Settings focus deterministic.

* test(e2e): wait for loaded navigation state

Expose the completed settings bootstrap state on the sidebar and wait for it before choosing a Classic or grouped fallback. This prevents E2E helpers from acting on the initial layout default.