dsh-session-recovery: Recover DSH session and memory from raw disk

`dsh-session-recovery` is an MIT-licensed recovery tool developed specifically for DeepSeek Harness (DSH). It is designed to directly read and reconstruct data from a raw disk when session logs (`session.jsonl.zstd`) or the memory database (`memory.db`) have been accidentally deleted, overwritten, or corrupted. The tool includes recovery scripts and a Web UI plugin. Its core functions include: 1. Locating SQLite headers within the raw disk and recovering readable data from `memory.db` using the `.recover` mechanism; 2. Scanning for zstd frames on the disk, splitting them by session, and reconstructing the official format `session.jsonl.zstd`; 3. Automatically fixing structural issues such as sequence numbers and event references in the reconstructed files.