Samples: Improve Hand-Eye GUI usability and fix bugs

[csu-bot-zivid]

Usability improvements and bug fixes across the Hand-Eye GUI sample and its shared widgets.

New features

• Load an existing hand-eye transform from a YAML file (File > Load HE Transform) to jump straight to verification, touch, or stitching without
  recalibrating. The tutorial checklist shows whether a transform is loaded,
  and a dialog displays the 4x4 matrix.
• Calibration status feedback: after calibrating, a colored banner reports
  the result (OK / insufficient motion / poor data quality) with guidance on
  what to do next.
• Save the stitched point cloud to a PLY file directly from the Stitch tab.
• Full touch-tool transform: configure a complete pose for the touch tool
  (position and orientation) instead of only a Z offset, via an advanced pose
  editor.
• Copy / Save As buttons and the saved file path in the calibration-result
  and transform dialogs.
• On-demand loading: previously captured pose pairs and infield-correction
  data are loaded from disk only when you ask for them, so a session opens
  faster.
• Reset to Defaults action to clear saved configuration.

Fixes

• Release captured frames when pose pairs or infield data are cleared, fixing a
  growth in memory use over a session.
• Rotation input no longer rejects valid Euler angles; gimbal-lock orientations
  that have no unique representation are now flagged with a warning.
• Stale or invalid saved settings are recovered gracefully on startup instead
  of preventing the GUI from launching.
• Infield-correction data loads correctly when the camera is disconnected.
• The settings dialog no longer lingers when calibration-board capture fails.
• Restored zoom and scrolling in the detection image viewer and fixed a
  squished calibration image.
• The GUI keeps running if the point cloud visualizer cannot start.
• The verification checklist refreshes when a transform is loaded, and drawing
  the projector overlay no longer crashes on unexpected detection counts.
• The eye-in-hand / eye-to-hand option is pre-selected from the saved
  configuration.

Usability

• Deleting all pose pairs now asks for confirmation first (it removes files
  from disk).
• The touch confirmation resets when the touch settings change.
• "Confirm marker to touch" is renamed to "Apply Touch Settings".
• Completed tutorial steps use colored checkmarks.
• Pose input fields have axis labels and larger fonts.