[Evaluation] Prepare azure-ai-evaluation 1.18.1 release

[slister1001]

Prepare azure-ai-evaluation 1.18.1 release (patch)

Cuts the next azure-ai-evaluation release as a patch (1.18.1). The changes since 1.18.0 are bug fixes + internal changes only — no new public API, features, or breaking changes — so this is a patch, not a minor.

CHANGELOG correction

The post-1.18.0 fixes had been merged under the already-published 1.18.0 header while 1.18.1 (Unreleased) sat empty. This PR moves them into 1.18.1 and stamps the release date:

• Bugs Fixed → moved to 1.18.1:
  • Enable azure_ai_search / azure_fabric / sharepoint_grounding tool calls for TCS/TOU ([Evaluation] Enable azure_ai_search/azure_fabric/sharepoint_grounding tool calls for TCS/TOU #47748)
  • OpenAPI tool-call validation in tool evaluators ([Evaluation] Align shared evaluator utils/validators/base with azureml-assets builtin #47840)
• Other Changes → moved to 1.18.1:
  • openapi_call / openapi_call_output message normalization ([Evaluation] Align shared evaluator utils/validators/base with azureml-assets builtin #47840)
  • Log-redaction of raw customer payloads ([Evaluation] Align shared evaluator utils/validators/base with azureml-assets builtin #47840)
• 1.18.0 retains only its two genuinely-shipped entries (EvaluationException normalization, RedTeam.scan() plaintext fix).

_version.py is already 1.18.1. CHANGELOG-only change — no source/tests touched.

Draft until the release pipeline / APIView / approvals are ready. Merging begins the code-freeze / ASK MODE window.

[Copilot]

Pull request overview

This is a CHANGELOG-only bookkeeping correction that cuts the azure-ai-evaluation 1.18.1 patch release. After 1.18.0 was published (2026-07-06 18:46 UTC), several bug-fix/internal PRs were merged with their notes placed under the already-shipped 1.18.0 header while the 1.18.1 (Unreleased) section sat empty. This PR moves those post-1.18.0 entries into a dated 1.18.1 (2026-07-09) section, leaving 1.18.0 with only the two entries it actually shipped.

I verified the categorization against the actual release history:

• The published 1.18.0 release notes contain only the EvaluationException normalization and RedTeam.scan fixes — exactly what remains under 1.18.0 here.
• PR #47840 merged ~2 minutes after 1.18.0 was published, and PR #47748 merged two days later, so their entries correctly move to 1.18.1.
• _version.py is already 1.18.1, matching the new CHANGELOG header.

Changes:

• Replace the empty 1.18.1 (Unreleased) placeholder with a dated 1.18.1 (2026-07-09) section.
• Move the tool-call enablement (#47748), OpenAPI tool-call validation, OpenAPI message normalization, and log-redaction entries into 1.18.1.
• Keep only the two genuinely-shipped entries under 1.18.0.