DSH Plugin Zen UserAgent: Fixing the DSH Plugin for OpenCode ZEN Free Model 429

`dsh-plugin-zen-useragent` is a DSH plugin maintained by `jiujiezongheti`, designed to resolve the issue where requests using OpenCode ZEN free models are incorrectly identified as `deepseek-harness` and return a `429 FreeUsageLimitError` because the request headers are not applied correctly. The plugin uses a patch mechanism to ensure that custom request headers (e.g., `User-Agent`) configured in provider settings override the default `attribution` field, allowing API requests to be correctly recognized as `opencode` clients. The plugin supports idempotent execution and automatically reapplies patches after DSH upgrades; if it detects code structure changes or write failures, it handles them accordingly.