dsh-retry-boost: Automatic Retry for DSH Transient Gateway Failures

`dsh-retry-boost` is a DeepSeek Harness (DSH) plugin designed to address transient failures encountered when integrating with gateways such as SenseNova. Since DSH does not retry specific error codes like `QUOTA` by default, the plugin enhances the `retryPolicy` through hot injection to cover all `llm-pi-ai` providers. It offers automatic injection at startup, automatic completion at runtime, and exponential backoff retries with jitter. Supporting three strategies and two modes, the plugin can effectively handle `429` errors and prevent tasks from being interrupted abruptly. It takes effect immediately after installation without requiring a restart, serving as the "first line of defense" against task failures caused by transient network fluctuations.