.NET: Add Foundry Agents Tool Sample - Memory Search

[rogerbarreto]

Motivation and Context

• Python: Integrate directly with Foundry Tools from agents using any chat clients #3674

Adds a sample demonstrating how to use the Memory Search tool with Azure Foundry Agents, enabling agents to recall information from previous conversations.

Description

Adds FoundryAgents_Step26_MemorySearch sample that shows:

• Creating a memory store with user profile and chat summary support via MemoryStores.CreateMemoryStoreAsync
• Configuring and attaching a MemorySearchTool to an agent
• Memory scope isolation per user
• Multi-turn conversation where the agent recalls previously shared information
• Inspecting MemorySearchToolCallResponseItem results from agent responses
• Full resource cleanup (agent + memory store)

The sample is aligned with the official Azure SDK for .NET Memory Search sample.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

[Copilot]

Pull request overview

This PR adds a new sample demonstrating the Memory Search tool integration with AI Agents in the Azure AI Foundry Agent Framework. The sample shows how agents can recall information from previous conversations using memory stores.

Changes:

• Added a complete Memory Search tool sample with documentation
• Implemented agent creation with memory store integration and user profile persistence
• Demonstrated memory indexing, retrieval, and cleanup workflows

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
README.md	Provides comprehensive documentation for the Memory Search tool sample, including prerequisites, environment variables, and expected behavior
Program.cs	Implements the complete sample showing memory store creation, agent configuration with Memory Search tool, conversation flow, and resource cleanup
FoundryAgents_Step26_MemorySearch.csproj	Defines project configuration targeting .NET 10.0 with necessary Azure AI dependencies