Persist widget state across area detector module open/close

[Osayi-ANL]

Problem:
Widget state in the viewers (colormap selection, intensity/level values, etc.) is lost every time a viewer is closed and reopened. Users must manually reconfigure these settings each session, which is disruptive to normal workflow.

Possible solution:
Introduce a StateManager with a single save_state() entry point that reads the current input and widget states from the area detector docks and persists them via QSettings. On reopen, the viewer calls a corresponding restore_state() before displaying, so all values are loaded from the previous session.

Acceptance criteria:

• Change the colormap in the area detector dock — the colormap matches what was set before closing
• Change the intensity/level values in the area detector dock and close the window — the intensity/level values match what was set before closing
• Change the intensity/level values in the HKL3D viewer and close the window-- the intensity/level values match what was set before closing
• In any of the viewers have this persistance kept for opening and closing