docs(openapi): align GET /models examples and parameter semantics

[akhilmmenon]

Description

This PR updates the OpenAPI spec for GET /models to match the current models API behavior and avoid confusion in generated docs/examples.

What changed

• Updated x-code-samples to use ai_service=openai instead of provider=openai:
  • cURL (default + self-hosted)
  • Python SDK examples (extra_query)
  • JavaScript SDK examples (client.models.list)
• Clarified query parameter descriptions:
  • ai_service: AI service(e.g. openai, anthropic)
  • provider: virtual key slug (provider segment in @provider/model)
  • limit: maximum models returned per page/request
  • offset: number of models to skip before collecting results
  • sort: clarified that provider sort refers to virtual key slug

Why

The previous docs examples implied filtering with provider=openai, which conflicted with intended semantics and caused implementation/documentation mismatch. This update ensures docs and API behavior stay consistent and reduces integration errors for users.

Validation

• Verified GET /models parameter block and all code samples render with updated query params.
• Confirmed examples are consistent with current backend contract for models endpoint filtering and pagination semantics.

[Copilot]

Pull request overview

Updates the OpenAPI spec for GET /models so the documented query parameters and generated code samples reflect the endpoint’s current filtering and pagination semantics (notably using ai_service for filtering by AI service rather than provider).

Changes:

• Clarified GET /models query parameter semantics for ai_service, provider, limit, offset, and sort.
• Updated x-code-samples (cURL, Python extra_query, JS client.models.list) to filter via ai_service=openai instead of provider=openai.

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[Copilot]

Minor consistency: this description uses single quotes around example values ('openai', 'anthropic'), but most other parameter descriptions in this spec either omit quotes or use backticks for inline code (e.g., "AI provider organization (e.g., openai, anthropic)" at openapi.yaml:33920). Consider aligning the formatting to match the rest of the document.

[Copilot]

The self-hosted samples use a different placeholder (YOUR_SELF_HOSTED_URL) than the rest of the spec and the declared DataPlaneServers (SELF_HOSTED_GATEWAY_URL). Consider switching these self-hosted examples to SELF_HOSTED_GATEWAY_URL for consistency (this placeholder also appears in the adjacent Python/JS self-hosted samples at openapi.yaml:5103 and :5135).