Issue: Backward Live Projection Stability 2026-08-20

issue023 [ ] Backward deletion can republish a stable projection

Status: Runtime fix verified by task038; user-visible confirmation remains pending.
Summary: Live row crossing treats forward typing and backward deletion identically. After a forward crossing, deleting a suffix into the previous native row can republish earlier rows and visibly move already typed text.
Expected vs Actual: The current live-edit contract preserves unaffected committed projection anchors during local tail shrink. Actual ekp-buffer--live-row-crossed-p triggers a full prefix publication in both directions.
Related: postmortem/20260730-incremental-live-append-ownership.md, ekp-buffer.el, task038.
Fix: A live row crossing now commits only when the native row moves forward; backward tail shrink keeps the transaction local.
Verification: Public edit-path regression and source-first full/random/ isolated ERT all pass.
Resolved At: Pending user-visible confirmation.
Resolved By: Developer implementation and verification.
Commit: Pending hardening commit.