deepseek-harness-fullstack: Break down full-stack development experience into four callable tools.

`redkiller79/deepseek-harness-fullstack` is a persona plugin for DeepSeek Harness representing a full-stack engineer, identified as `dsh-fullstack-engineer`. It registers three skills—full-stack development, frontend design engineering, and browser automation—originally scattered across expert packages, into four tools: `fullstack_guide`, `frontend_studio`, `browser_automation`, and `read_skill_asset`. The skill content is injected into the context only when invoked, avoiding permanent prompt space, and supports the `focus` parameter for direct access to sub-topics. It requires Node.js ≥ 22.14.0 and DSH 0.2.x. Installation is performed using `dsh plugin --profile web add github:redkiller79/deepseek-harness-fullstack`, followed by restarting the profile to apply changes. The package includes an offline smoke test script (`node test/smoke.mjs`). The plugin runs with the current DSH process permissions; please review `index.js` before installation. It is licensed under MIT.