Auto Nest nests the remaining quantities on sheets like the shown plate
with the saved engine selection (plug-ins loaded as in the desktop app),
solving off the UI thread with shared progress text in the status bar.
The button becomes Stop, which discards the whole proposal; Open is
refused while it runs. A refused result changes nothing and says why.
--auto-nest runs it on the opened nest before --snapshot renders, and
the snapshot now writes the status line to <png>.txt for headless checks.
The engine selection and the whole-job progress adapter use only Engine
and Data, so they move into the toolkit-neutral library for the Avalonia
front end to share. The namespace stays OpenNest.Forms, so WinForms
callers are unchanged.
Linux tests now cover the adapter's stage routing, one-based plate
numbers and descriptions, and the fill-strategy mapping; the saved
selection is left out because it reads and writes the real per-user file.
Document and Undo/ (ChangeScope, NestFingerprint, NestUndoState) use
only Core, Data, IO and Engine, so they move into the toolkit-neutral
library both desktop front ends share. Namespaces are unchanged, so the
WinForms app compiles as before; it keeps using the internal scope
factories and fingerprint through InternalsVisibleTo.
The scope, fingerprint and SaveAs/save-point rules now have Linux tests
in OpenNest.Desktop.Tests; before, only the Windows-only WinForms suite
covered them.
aj