Edits in the Cutting Parameters dialog only reached user settings, while a
plate's stored parameters took priority, so a change was lost on any
planned plate unless Apply succeeded. User settings now win; a plate's own
are the fallback when none are saved or readable.
WinForms tests saved to the real user-settings.json, and with user settings
winning a test's lead-ins would feed real planning, so they now use a temp
file and skip the legacy settings carry-over.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>