dsh-auto-evolve: DeepSeek Harness Self-Evolution Plugin

`dsh-auto-evolve` is a self-evolution plugin for DeepSeek Harness (DSH) designed to automate the maintenance of agent skills and strategies. It observes runtime signals, uses an LLM to propose changes, and strictly validates them in a sandbox. The plugin supports automatic rollback and cost control, offers three evolution modes—`observe`, `propose`, and `auto-apply`—and reduces maintenance costs while improving stability through a closed-loop process.