fix(api-proxy): OpenCode port 10004 defaults to Copilot/OpenAI routing instead of Anthropic (#1979)

* Initial plan

* fix: update OpenCode proxy to default to Copilot/OpenAI routing

* fix: address code review - correct comment to use COPILOT_AUTH_TOKEN

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Landon Cox <landon.cox@microsoft.com>

Author: Copilot