Fused convenience: caret if editing, else start an edit. Prefer startEditWith (sheet flavor)
or insertAtCaret (editor override) directly so the flavor is chosen by the resolving scope,
not a runtime session check; this is kept while the sheet/editor split is wired through.
Fused convenience: caret if editing, else start an edit. Prefer startEditWith (sheet flavor) or insertAtCaret (editor override) directly so the flavor is chosen by the resolving scope, not a runtime session check; this is kept while the sheet/editor split is wired through.