dsh-bike-fit: Saddle Adjustment Plugin

`dsh-bike-fit` is a DeepSeek Harness (DSH) client plugin maintained by developer `uckkk`, designed specifically for saddle adjustment logic in the cycling domain. It runs in a local Node.js environment without relying on network requests and generates cycling plans using the `bike_fit` tool. Installation requires the `dsh plugin add` command, and it depends on the `@deepseek-ai/cordis` and `@deepseek-ai/dsh-tools` libraries. It provides the DSH ecosystem with a lightweight, offline-capable cycling data processing capability.