dsh-plan-first-dev: DSH Plugin that Automatically Enters Plan Mode Before Development

`dsh-plan-first-dev` is an MIT-licensed plugin for DeepSeek Harness (DSH) designed to establish "plan first, implement later" as the default behavior for code development tasks. Installed at the profile layer, the plugin listens for session creation events; upon detecting a new session, it automatically enables plan mode while retaining the user's permission to manually disable it. For development tasks, the plugin enforces a workflow where the model must submit a complete plan—encompassing architecture, changed files, API changes, and testing standards—before implementation is permitted, requiring user approval via `exit_plan_mode`. For non-development tasks such as writing and data analysis, the plugin registers a `no_plan_required` tool, allowing the model to identify the task type and exit plan mode directly for execution without requiring plan approval.