dsh-tsien-hsue-shen: Add Engineering Cybernetics-style project method to DSH

dsh-tsien-hsue-shen is a community plugin for DeepSeek Harness (dSH) released by Tostoevsky, licensed under the MIT License. Distilled from the methodology of Qian Xuesen's *Engineering Cybernetics*, it aims to address the lack of stable methodological frameworks in agents handling complex projects—specifically issues such as unclear objectives, invisible states, unidirectional feedback loops, and ambiguous stopping criteria. The plugin provides a skill named "tsien-hsue-shen" comprising 13 thematic chapters. Its core functionality involves conducting methodological reviews of project planning, execution, or retrospectives, focusing on goal definition, observability, controllability, feedback loops, uncertainty handling, and stopping rules. This assists agents in redefining problems, identifying leverage points, and determining the optimal time for delivery. Installation requires Node.js version ≥ 22.19 and is available via npx @deepseek.