UserSettingsFile in OpenNest.Data reads and writes
%APPDATA%\OpenNest\user-settings.json (~/.config/OpenNest on Linux) so the
Avalonia app can share the settings the WinForms app keeps there.
AppDataSettingsProvider now delegates its file reads and writes to it, so
there is one implementation of the format.
A missing, unreadable or corrupt file reads as empty without touching it,
and Update keeps entries the caller does not change. One difference for
WinForms: an entry whose value is not text is now skipped instead of the
whole file reading as empty.
aj
b92d079e77