- NewTaskSheet declares its own screen `layout`, and React Navigation
  resolves `screen.layout ?? group ?? navigator screenLayout`, so the route
  silently bypassed the navigator-level seam. It now renders
  GuardedScreenLayout inside its own layout, wrapping the whole flow (and
  NewTaskFlowProvider) with a comment noting the override rule.
- The split-view workspace sidebar and inspector render in RootStackLayout,
  outside every screen slot. Give ThreadNavigationSidebar and
  WorkspaceInspectorPane their own scoped boundaries so a pane failure
  spares the open thread and the rest of the workspace.
- In split view the Thread route stays mounted across sidebar selections;
  screen boundaries now take resetKeys from the route params so a new
  thread does not inherit the previous route's failure state.
- Drop the WeakSet identity dedupe from the render-error log: a cached
  error re-thrown on retry is a fresh incident, and identity dedupe would
  swallow it. Once a boundary recovers, the throw stops bubbling, so
  nested double-recording was not happening anyway.