[Luca Schiavone (Overvolted)]

Motivation and Context

#14682 removed the .NET Milvus connector and points to the provider in CommunityToolkit/AI.

This PR adds Milvus to the multi-store vector search sample and the VectorStoreRAG demo, using CommunityToolkit.VectorData.Milvus. It follows the Chroma sample additions in #14602.

Description

• Add VectorStore_VectorSearch_MultiStore_Milvus, with examples using and without dependency injection.
• Add a Docker fixture running Milvus 2.6.25 with embedded etcd and local storage, including a readiness check and container cleanup.
• Link the Milvus example from the common class and the other vector store examples.
• Add Milvus as a Rag:VectorStoreType option in VectorStoreRAG, with host, port, TLS, API key, and database configuration.
• Document how to start Milvus locally and configure a remote endpoint.
• Reference CommunityToolkit.VectorData.Milvus 1.0.0-preview from both sample projects.

Contribution Checklist

• The code builds clean without any errors or warnings
• Formatting checks pass for the changed implementation files
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[Luca Schiavone (Overvolted)]

@microsoft-github-policy-service agree