batch-edit 2

Hash-anchored read/edit/undo_last_edit tools for DeepSeek Harness (dsh). Every line gets a unique 3-char hash (A-Za-z0-9) that stays stable across edits; stale or ambiguous anchors are rejected, never fuzzy-matched. Undo persists across restarts.

Line-anchored read/edit/batch_edit/grep/undo_last_edit tools for DeepSeek Harness (dsh). Every line is addressed by `<line>:<anchor>` so chained edits skip a re-read; stale or ambiguous anchors are rejected and a fresh `<line>:<anchor>` is served back. Un