Frame now carries view state (scale/focus/query) to the main goroutine,
which reads only the frame-receiver-stored snapshot. Renderer owns Gio
widget editors (registered by ID) and the draw scale. Autosave timer
sends a token to the logic goroutine instead of touching state;
Shutdown waits for the owner to exit before FlushAll.
Tests access state only through owner-side Inspect/WithState helpers
(harness + in-package). Fixed double-Harness.Run race in two e2e tests,
made TestWorkerPool_PriorityPreemption deterministic, and raised the
lazy-loading test timeout that was too short under -race.
go test -race ./... is now green.
When directory navigation fails (e.g., permission denied on Android),
the browser now restores the previous path instead of staying in a
broken empty state. NavigateTo saves the current path to History, and
handleError restores it and re-builds the index for the previous
directory when a BuildIndexTask fails.
