dsh-goal-auto: DeepSeek Harness Long-Session Auto-Recovery Plugin

`dsh-goal-auto` is a session-level automatic recovery plugin for DeepSeek Harness (DSH), designed to address the issue of long-running goal sessions failing to automatically recover after a Harness restart. The plugin provides a toggle button in the session header and an HTTP API, allowing it to automatically reload the agent on restart, mount presets, re-arm the goal, and keep the driver running. It handles session recovery only and must be used together with an external process watchdog to monitor the health of the Harness process.