add: machine-local window layout persistence (#85, part 1)

[Osayi-ANL]

First of eleven parts for #85.

A window reopens at the size, position and dock arrangement it was closed at. State goes to QSettings("DashPVA", <viewer type>) — Qt's per-user store, so nothing lands in the repo, and each viewer gets its own keys.

DOCK_STATE_VERSION guards the dock layout: raise it when a viewer's dock set changes and a stale layout is retired rather than restored into the wrong places.

Restore runs on a deferred singleShot once __init__ has finished. Docks cannot be restored before they exist, and a subclass's hardcoded defaults would otherwise overwrite restored values. Living in BaseWindow means no window can forget to.

HKL3D and Workbench get this by inheritance — neither file is touched. The area-detector viewer sets persist_state = False for now because it still restores its own area_det_* keys; that comes off in part 4 when it migrates onto the shared store.

Inputs and session restore follow as parts 2 and 3.

Test Plan

• Open HKL3D
• Move it to a new location on the screen and change the geometry(shrink window or enlarge)
• Close HKL3D and Open it -- It stays persistent
• Do the same with the workbench

[pecomyint]

Please add focused save/restore/version tests, use a per-viewer dock-state version, and remove the 1.1.2 version bump. The BaseWindow consolidation otherwise matches #85 part 1.

[pecomyint]

Merge this before viewer-specific persistence work; #175 and #190 should then be updated against it so closeEvent preserves both layout saving and teardown