Add binary morphology commands

[yangfei]

Summary

Add baseline binary morphology commands for thresholded/binary workflows.

Scope

• Implement erode, dilate, open, and close in core code.
• Add app menu commands where appropriate.
• Define behavior for grayscale input clearly.
• Add deterministic core tests.

Acceptance criteria

• User can run erode and dilate on supported image data.
• User can run open and close on supported image data.
• Invalid or unsupported input fails clearly.
• Core morphology behavior has automated tests.