Add SDK support for workspace connector skill docs

The new Cloud workspace connector documentation endpoint needs typed SDK support when its public specification is published.

Platform implementation: https://github.com/airbytehq/airbyte-platform-internal/pull/19464.

Add `GET /v1/workspaces/{workspaceId}/skills/docs` under the Workspaces SDK group (`getSkillDocs` alias). Require `id=connector-source:`; accept an optional exact `section` from the default response outline. The identifier is a source instance UUID, not a connector definition ID.

Preserve the complete typed response: `metadata`, `outline`, nullable `section_id`, and `content`; metadata includes freshness and warnings. Support all five content block variants (`heading`, `paragraph`, `list`, `code`, `table`), explicit nullable fields, empty arrays, and `kind=connector_source` only. Library skills are excluded.

This read-only endpoint returns YAML-derived documentation, which can describe capabilities outside Cloud source execution's current scope. Reading docs grants no execution access. Availability is controlled and defaults off; workspace reader access, existing Agents enrollment, and source enablement are required. Handle sanitized problem responses for 401, 403, 404, 413, 422, 501, 502, 503, and 504.

- [ ] Regenerate from the published `api_sdk.yaml` and expose the Workspaces operation and typed models.
- [ ] Add wire tests for default docs and exact-section requests, all five block variants, explicit nulls, empty arrays, warnings, and sanitized problem responses.
- [ ] Coordinate the SDK release with public-spec publication and Cloud rollout.

Paired E2E remains pending. This issue tracks generation and release; it does not claim an SDK release or production activation.

Once the public api_sdk.yaml is published, start by regenerating the SDK and inspect the Workspaces operation and typed models for getSkillDocs. Add wire coverage for default and exact-section requests, all five content blocks, nulls, empty arrays, warnings, and sanitized problem responses. Done means the generated operation and models are exposed and release coordination is ready for spec publication and Cloud rollout.

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