dsh-resume-plugin: Continue Codex and Claude Code sessions in DeepSeek Harness

dsh-resume-plugin is an MIT-licensed plugin (v0.1.0) developed specifically for DeepSeek Harness (DSH), designed to convert external session logs from Codex or Claude Code into the working context of the current DSH session. Utilizing the two skills `/resume-codex` and `/resume-claude`, the plugin reads selected external session history, generates concise handover summaries, and verifies the current repository state, thereby allowing users to continue working directly in DSH without starting or reassigning tasks to the original agent. The plugin adopts a security-first processing mechanism, treating external records as untrusted static history. Its shared reader excludes system/developer messages and reasoning.