feat(core): support Responses API with configuration and documentation

[EAGzzyCSL]

Summary

Add an opt-in OpenAI Responses protocol through MIDSCENE_MODEL_API_TYPE="responses", including separate Planning and Insight configuration. Chat Completions remains the default.

• Add streaming and non-streaming Responses calls, message conversion, and usage normalization through the shared model-call lifecycle.
• Add adapter protocol support declarations and GPT Responses parameter handling; separate image-detail and semantic-retry temperature policies.
• Serialize assistant text history correctly for Responses requests.
• Add bilingual protocol guidance and a Chat / Responses selector within GPT configuration examples. Update connectivity checks and Azure image-detail troubleshooting.

Validation

• pnpm run lint — passed.
• pnpm --filter doc exec rspress build — passed during documentation development.
• Browser checks for protocol switching, model-role examples, and help links — passed.
• Mocked execution of both bilingual curl examples for Chat and Responses — endpoint and JSON body verified.
• pnpm exec nx build doc — blocked by the local environment's missing GITHUB_TOKEN; the non-strict Rspress build above passed.

Full runtime tests were not rerun at PR creation.

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