Slate v2 Op-family Twentieth Slice

Supporting plan. For current queue and roadmap truth, see master-roadmap.md.

Goal

• Cash out the broader mixed-inline Editor.before(...) / Editor.after(...) seam into Transforms.move(...).

Scope

• Keep distance, reverse, and edge.
• Support moving across sibling text leaves inside one supported top-level block, including inline descendants.
• Keep start / end resolution from selection direction.
• Avoid cross-block movement and unit parity in this slice.

Phases

• Confirm the mixed-inline move semantics and the current location seam
• Write focused failing tests
• Implement the smallest honest core/API slice
• Sync package/public docs
• Verify the touched package/docs