Update Microsoft.Extensions.AI changelog files with current NuGet versions (#6849)

* Initial plan

* Update Microsoft.Extensions.AI changelog files with current NuGet versions

Co-authored-by: stephentoub <[email protected]>

* Correct OpenAI and AzureAIInference package versions to 9.9.1-preview.1.25474.6

Co-authored-by: stephentoub <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: stephentoub <[email protected]>

Author: Copilot

src/Libraries/Microsoft.Extensions.AI.Abstractions/CHANGELOG.md

@@ -1,6 +1,6 @@
 # Release History
 
-## NOT YET RELEASED
+## 9.9.1
 
 - Added new `ChatResponseFormat.ForJsonSchema` overloads that export a JSON schema from a .NET type.
 - Added new `AITool.GetService` virtual method.

src/Libraries/Microsoft.Extensions.AI.AzureAIInference/CHANGELOG.md

@@ -1,6 +1,6 @@
 # Release History
 
-## NOT YET RELEASED
+## 9.9.1-preview.1.25474.6
 
 - Updated to accommodate the additions in `Microsoft.Extensions.AI.Abstractions`.
 

src/Libraries/Microsoft.Extensions.AI.OpenAI/CHANGELOG.md

@@ -1,6 +1,6 @@
 # Release History
 
-## NOT YET RELEASED
+## 9.9.1-preview.1.25474.6
 
 - Updated to depend on OpenAI 2.5.0.
 - Added M.E.AI to OpenAI conversions for response format types.

src/Libraries/Microsoft.Extensions.AI/CHANGELOG.md

@@ -1,6 +1,6 @@
 # Release History
 
-## NOT YET RELEASED
+## 9.9.1
 
 - Updated the `EnableSensitiveData` properties on `OpenTelemetryChatClient/EmbeddingGenerator` to respect a `OTEL_INSTRUMENTATION_GENAI_CAPTURE_MESSAGE_CONTENT` environment variable.
 - Updated `OpenTelemetryChatClient/EmbeddingGenerator` to emit recent additions to the OpenTelemetry Semantic Conventions for Generative AI systems.