dsh-check-for-updates: DSH Security Update and Integrity Check Plugin

The dsh-check-for-updates plugin is designed to resolve startup crashes caused by replacing native modules during DeepSeek Harness (DSH) upgrades. It employs a decoupled two-stage update mechanism that schedules installation tasks to be executed by an independent process after DSH exits, combined with post-installation triple verification and a startup self-check to ensure module integrity and system stability. The plugin supports automatic checks, manual checks, one-click upgrades, and network debugging, and it installs easily without requiring manual enabling, making it a valuable tool for improving the safety of DSH updates.