Fix unused volume variable in workspace analyzer

[Copilot]

Description

Addresses review feedback from #14: the volume variable was calculated but never used.

Fixed by including the workspace volume in the log output alongside the existing axis dimension information:

logger.log_info(
    f"Computed Cartesian workspace bounds from {len(workspace_pts)} FK samples:\n"
    f"\t X-axis: [{min_bounds_np[0]:.3f}, {max_bounds_np[0]:.3f}] m (range: {dimensions[0]:.3f} m)\n"
    f"\t Y-axis: [{min_bounds_np[1]:.3f}, {max_bounds_np[1]:.3f}] m (range: {dimensions[1]:.3f} m)\n"
    f"\t Z-axis: [{min_bounds_np[2]:.3f}, {max_bounds_np[2]:.3f}] m (range: {dimensions[2]:.3f} m)\n"
    f"\t Volume: {volume:.3f} m³"
)

Fixes feedback from #14 (comment)

Type of change

• Bug fix (non-breaking change which fixes an issue)

Screenshots

N/A - logging output change only.

Checklist

• I have run the black . command to format the code base.
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• Dependencies have been updated, if applicable.

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