dsh-md-memory: A Markdown File Memory Plugin for DeepSeek Harness

The `dsh-md-memory` plugin for DeepSeek Harness (DSH) provides agents with a lightweight, persistent memory solution. By storing memory as Markdown files (such as `user.md` and `agent/MEMORY.md`), it enables simple management of cross-session memory without relying on vector databases or automatic extraction. After installation, the model must explicitly call tools to perform read and write operations. This approach restricts write permissions for subagents and enforces file size limits (such as an 8KB limit for `user.md`). It does not support automatic extraction or vector search, making it suitable for scenarios that require transparent configuration and maintained controllability.