fix(opencode): remove invalid native runtime stream fields

Author: rustybret

packages/opencode/src/session/llm.ts

@@ -223,8 +223,6 @@ const live: Layer.Layer<
           provider: item,
           auth: info,
           llmClient,
-          isOpenaiOauth: prepared.isOpenaiOauth,
-          system: prepared.system,
           messages: prepared.messages,
           tools: prepared.tools,
           toolChoice: input.toolChoice,