dsh-startup-model: Let DSH remember the last used model

dsh-startup-model is a DeepSeek Harness plugin maintained by zxzc114514 (MIT, v1.0.0, categorized as "Memory") that solves the inconsistency between the default model for new sessions and the model used before exiting, as well as the need to repeatedly switch models upon every startup. It listens for model/selection or request/header events, atomically writes the model triple (provider/model/reasoningEffort) to the local state file after a 500ms debounce, and restores it upon startup via agentDefaultModel injection. It also features sub-agent isolation, Provider health degradation, and state file path configuration. Installation supports searching in the plugin marketplace and manually importing bundles via profile package.json, usually ready to use out of the box.