dsh-codex-context: Lossless Retrieval Context Manager for DeepSeek Harness

`dsh-codex-context` is a plugin for DeepSeek Harness (DSH) designed to address context window exhaustion and information loss caused by the default LLM summarization backend. It employs mechanisms such as token-budget-based sliding windows, zero-orphan boundaries, and model-agnostic checkpoints to ensure information integrity in long sessions. The plugin provides tools such as persistent working notes and cold history search, and supports installation via Git or locally. When installing, be aware of potential tool name conflicts and regular expression query limitations.