DSH crash-rescue plugin: undo config & plugin-code changes, secret-safe snapshots, one-click SAFE MODE, plus offline CLI/GUI that work even when DSH won't boot.

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.