Add SemanticKernel rate limit middleware

[dianadiazbisbe]

Description

Introduces SemanticKernelRateLimitMiddleware . Also updates LogAIRequestScopeMiddleware to public and adds Microsoft.SemanticKernel package reference. Version suffix updated to preview-09.

Motivation and Context

Migrating a new middleware to handle 429 rate limit exceptions from Semantic Kernel and return appropriate HTTP responses, and necessary packages.

Type of change

Please check only those options that are relevant with a (✅).

• [✅] The code builds clean without any errors or warnings
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist

Please check all options from this checklist when validating your pull request with a (✅).

• [✅] My code follows the style guidelines of this project
• [✅] I have performed a self-review of my own code
• [✅] I have commented my code, particularly in hard-to-understand areas
• [✅] I have made corresponding changes to the documentation
• [✅] My changes generate no new warnings
• [✅] Any dependent changes have been merged and published in downstream modules
• [✅] I didn't break anyone 😄

[Copilot]

Pull Request Overview

This PR adds rate limit handling for Semantic Kernel operations by introducing a new SemanticKernelRateLimitMiddleware that intercepts HTTP 429 (Too Many Requests) exceptions. It also makes the LogAIRequestScopeMiddleware public for external usage, adds the Microsoft.SemanticKernel package dependency, and updates the version suffix to preview-09.

Key changes:

• New middleware to handle rate limiting from Semantic Kernel APIs with retry-after header support
• Changed LogAIRequestScopeMiddleware visibility from internal to public
• Added Microsoft.SemanticKernel 1.64.0 package reference

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
src/Encamina.Enmarcha.Agents/Middlewares/SemanticKernelRateLimitMiddleware.cs	New ASP.NET Core middleware that catches HttpOperationException with 429 status codes from Semantic Kernel and returns appropriate HTTP responses with retry-after headers
src/Encamina.Enmarcha.Agents/Middlewares/LogAIRequestScopeMiddleware.cs	Changed class visibility from internal to public for external consumption
src/Encamina.Enmarcha.Agents/Encamina.Enmarcha.Agents.csproj	Added Microsoft.SemanticKernel package reference (version 1.64.0) to support the new middleware
Directory.Build.props	Updated version suffix from preview-08 to preview-09 for the next release

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[rliberoff]

LGTM