.NET: deps/ai extensions

[Vincent Biret (baywet)]

Motivation & Context

Refresh the .NET dependency set to pick up newer AI provider, hosting, Aspire, AGUI, storage, identity, and Microsoft.Extensions package versions. This keeps samples and integration tests aligned with the current package ecosystem, removes now-unnecessary dependency overrides, and updates code that depends on renamed or serializer-sensitive APIs.

Description & Review Guide

• What are the major changes?

  • Updated centrally managed package versions, including Microsoft.Extensions.AI 10.10.0, OpenAI 2.13.0, ModelContextProtocol 2.2.0, AGUI 0.0.6, OllamaSharp 5.4.30, Anthropic 12.45.0, Azure.AI.AgentServer.Core beta.29, Cosmos 3.63.0, Azure.Storage.Blobs 12.29.2, Hyperlight 0.6.0, Microsoft Agents packages 1.9.28-beta, and related Aspire/identity packages.
  • Updated Foundry hosted agent samples to use Agent Framework 1.20.0-preview.260831.1 and matching dependency versions.
  • Removed Dapr sample central package transitive pinning workarounds that are no longer needed with the newer Microsoft.Extensions baseline.
  • Updated AGUI session persistence test helpers to pass serializer options with the AGUI source-generated resolver.
  • Updated the Anthropic skills sample to read LatestVersionID instead of the previous version property.

• What is the impact of these changes?

  • Keeps .NET samples and tests compatible with current dependency versions.
  • Simplifies sample project files by removing obsolete version overrides.
  • Preserves AGUI serialization behavior after the dependency updates by explicitly configuring the required serializer context.
  • Fixes the sample skill version output to use the correct property exposed by the updated package.

• What do you want reviewers to focus on?

  • Whether the dependency version set is internally consistent across central package management and sample-specific package references.
  • Whether the AGUI serializer option changes are the right long-term pattern for tests and host utilities.
  • Whether any sample projects still carry unnecessary direct version pins or warnings after the package refresh.

Related Issue

Fixes #

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Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR is linked to an issue and there is no other open PR for this issue (see Related Issue above).
• This is not a breaking change. If it is a breaking change, add the breaking change label (or add "[BREAKING]" to the title prefix, before or after any language prefix) — a workflow keeps the label and title prefix in sync automatically.