dsh-wsl-git: Truncated Git Status and Diff Summary Plugin

`dsh-wsl-git` is a WSL environment plugin for DeepSeek Harness (DSH), designed to address agent context window management issues. It provides lightweight Git summaries to avoid the noise of oversized diffs. Core features include checking Git availability, outputting a status summary, and reporting diff statistics. The plugin must run with the current process permissions, does not support commit or push operations, is compatible with DSH 0.1.2+, and is typically used together with `dsh-wsl-kit`.