Function restoreSnapshot

Restore camera + dim state from a snapshot.

• The camera position, target, up, near/far, and projection-specific parameters (fov for perspective, zoom for ortho) are written back in place. After updating, the controls are re-initialised so subsequent orbit/fly updates don't snap the camera back.
• Dims restore is best-effort: if the snapshot's ndim does not match the loaded dataset, the dims block is skipped with a warning. The displayed set is not changed (re-displaying dims would re-frame the scene); only the per-dim currentStep values are forwarded to sceneDimsManager.setDimensionValue.

Returns the parts that were actually applied so callers can confirm.