Moves startup and settings code out of MainForm:
- PostProcessorLoader discovers posts and registers their materials.
Each DLL now loads in isolation; a failing one is named in a startup
warning instead of throwing out of the MainForm constructor.
- MachineSettings owns the clamp-settings and nest-defaults entry points
and their once-per-session warnings; BomImportForm calls it directly.
- NewNestFactory creates File > New nests and their daily names;
GetNestName is now a pure static the characterization test calls.
- MainWindowSettings restores/saves window placement and migrates the
legacy nest template.
- UpdaterStatus owns the updater and its status-bar item.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>