dsh-plugin-guard: DeepSeek Harness Plugin Mount Guard

The plugin mounting mechanism in DeepSeek Harness (DSH) requires the `name` and `version` fields to be non-empty; otherwise, it throws an error and aborts the request. The `dsh-plugin-guard` plugin is designed to address this issue by mirroring the upstream parsing rules and providing a three-layer defense mechanism: startup self-healing, write monitoring, and a CLI tool. It can automatically repair a missing `package.json`, or audit, repair, and pre-check configurations via commands, ensuring plugin mounting remains compliant and preventing global request failures.