DSH Plan First Dev

Key features

• Autostartautomatically enter plan mode (interviewed/created, call planMode.set (agent, true) when a new session is created)
• @deepseek-ai/dsh-plan-mode (official plugin, with dsh installation, no additional installation)
• Session never happened plan/mode event ⁇ Autostart
• User has initiated /plan off or switched mode sessions Respect the status quo, resume does not overwrite user selection
• Enables a complete turn-off (reserved command layer enhancement) with config.defaultOn: false.