fix(multicursor): cascade mapping-edit during Visual selection #42027

Problem:
- A mapping that edits the buffer during a Visual selection applies only
  at the primary cursor. The edit "voids" the pending Visual-session,
  because `mc_vsel_refresh` only previews the selection per-cursor and
  must not edit.
- A cursor overlapping the primary applies an edit twice, if the
  command moves the primary before cascade ("yiwp").

Solution:
Cascade a Visual session's edits span-by-span, like an insert-session.
- Each span is prefixed with "gv" so per-cursor reselect works.
- Void only if no subatom was captured.
- Dedupe cursors against the primary's anchor at cmd start, not its
  position after.

0 files changed, 0 insertions, 0 deletions