xby-search-movie: DSH Movie Search and Validation Plugin

The DeepSeek Harness plugin `xby-search-movie` is designed to address the challenge of agents obtaining accurate playable links when processing video resources. It focuses on searching for and validating movies and TV series, with core features including setting an API key, executing a search to retrieve an unverified list of resources, and verifying link playability. Installation requires first registering to obtain a key and then running the specified command. During use, search first to obtain candidate results, then perform secondary validation using `validate_video_url` to ensure that the links delivered to users are usable, making it suitable for building video resource aggregation features.