Make the layout reconfigurable, the foundation for the redesign:
- The diffraction image becomes the central widget; the right-hand side panel
is now a dockable "Inspector" (QDockWidget, right area).
- Every dock and toolbar gets a stable objectName so QMainWindow saveState /
restoreState round-trips. Dataset-info docks are numbered uniquely.
- Persist geometry + dock state to QSettings on close and restore on launch,
so the user's arrangement resumes.
- New "View" menu with Image / Processing perspectives (show/hide the bottom
plots + jobs panel) and "Reset layout" (back to the as-built arrangement,
captured at startup).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>