dsh-peak-block: DeepSeek Official Peak-Hour Automatic Blocking

`dsh-peak-block` is a DeepSeek Harness (DSH) plugin designed to address higher billing costs or resource constraints on the official API during weekday peak hours (9-12, 14-18). It intercepts requests sent to `deepseek-official` and routes them to configured third-party or local endpoints. Core features include timezone-based automatic peak/off-peak detection, precise interception of specific paths, and provider switching. The `targetProvider` option specifies the target adapter; if left blank, requests are blocked directly. The plugin includes the 2026 statutory holidays list issued by the State Council, ensuring that holidays are treated as off-peak and are not overridden by peak/off-peak configurations. It takes effect after installation and restarting the Web interface.