dsh-client-ui-model-search: A Searchable Model Selector Plugin for DeepSeek Harness

`dsh-client-ui-model-search` is a lightweight UI plugin designed for DeepSeek Harness (DSH) to address the challenge of selecting a model from long lists in the Web Composer. It provides a top search box, tokenized AND matching, collapsible grouping, bilingual support, and theme adaptation. The plugin is registered non-destructively with `priority: -1` and becomes ready to use after installation and a restart, making it suitable for scenarios where users need to locate models efficiently in the DSH interface.