Slate v2 Op-family Twenty-fourth Slice

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

Goal

• Broaden Editor.before(...) / Editor.after(...) across supported top-level block boundaries and let Transforms.move(...) inherit that seam.

Scope

• Keep Point | Range and distance.
• Support walking across supported top-level blocks.
• Treat the boundary between block end and next block start as one step.
• Let Transforms.move(...) cash out the same broader location seam.
• Avoid Path support, unsupported blocks, and cross-block delete widening in this slice.

Phases

• Confirm the cross-block location semantics and current stepper behavior
• Write focused failing tests
• Implement the smallest honest cross-block stepper and move(...) follow-on
• Sync package/public docs
• Verify the touched package/docs