dsh-memory (Cairn): Persistent Memory for DeepSeek Harness

`dsh-memory` is a memory plugin for DeepSeek Harness (DSH), designed to address context loss after agent sessions end. It provides persistent cross-session storage with three-tier memory scopes: global, project, and user. The plugin leverages the BM25 algorithm for highly relevant retrieval and supports summary-first injection as well as step-level automatic recall. It also features automatic identity updates, security scanning, a deduplication pipeline, and two-tier lifecycle management, along with a management interface and manual review mechanism, making it suitable for complex task development that requires long-term context maintenance.