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.
NewLogic now takes (FileSystem, path, openfunc); update the e2e harness
and editor tests accordingly. The harness uses a no-op openfunc, matching
impl_other.go (the real app's OpenFile is a platform bridge, no-op off
Android).
Also adds doc/development_plan.md (draft, with corrections note re: the
live repo state).
