dsh-date-wrapper: Minimal Date Row for DeepSeek Harness Runtime Context Snapshots

`dsh-date-wrapper` is a Cordis plugin for DeepSeek Harness (DSH) that addresses the issue of the official plugin `dsh-time-context` adding redundant context. It compresses approximately 280 characters of date metadata into 46 characters (about 12 tokens) and attaches it to the runtime context snapshot rather than the message stream, thereby saving token budget and avoiding JSONL event writes. The plugin runs independently, without relying on external libraries or DSH source code modifications, and is enabled via the `cordis.patch.yml` configuration. After installation, you must set the IANA time zone (e.g., Asia/Shanghai) and restart. It is compatible with DSH 0.1.x and 0.2.0-rc.