Two small independent fixes

[pecomyint]

Primary-objective combo doesn't refresh on role changes

The Bayesian viewer's Primary-objective combo refreshed on add/remove/rename but
not when a row's Role changed (the role is a QComboBox cell-widget whose
changes were never wired up). Flipping an objective maximize→observe wrongly left
it in the Primary list.

• _ObjectiveTable now has an objectives_changed signal, emitted on any change
  to the optimized set (cell edits, add, remove, role/protocol combo changes).
  Rows are built under blockSignals so a half-built row can't fire a refresh.
• The viewer replaces its three ad-hoc connects with a single
  objectives_changed → _refresh_primary_combo.
• New headless regression test (tests/unit/test_bayesian_primary_combo.py).

Mask load: lossless transpose instead of downsampling resize

Loading a mask whose dimensions are simply swapped vs the detector (e.g. 100×400
on a 400×100 detector) only warned, then resampled it through skimage resize,
arriving badly downsampled.

• load_mask_clicked now detects the pure axes-swap case
  (mask.shape == img_shape[::-1]) and offers a lossless transpose that matches
  the detector at native resolution. Any other mismatch keeps the original
  warn + resize behavior.

[Osayi-ANL]

Nice