dsh-trustedrouter: The TrustedRouter Plugin for DeepSeek Harness

The `dsh-trustedrouter` plugin resolves the issue where DeepSeek Harness cannot write TrustedRouter policies into the request body. It wraps the `fetch` method to enable per-model privacy and routing policies to be configured in dsh. Users can set privacy levels, preferred providers, and other options through the web interface or a configuration file. The plugin only supports dsh web, depends on pnpm, stores its configuration in `cordis.patch.yml`, and requires manual upgrades.