Python: Add hosted agent samples

[TaoChenOSU]

Motivation and Context

Add hosted agent samples to Python.

Samples ported from .Net: https://github.com/microsoft/agent-framework/tree/main/dotnet/samples/HostedAgents

Description

Add hosted agent samples to Python.

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 three Python hosted agent sample demos, ported from the .NET samples. The samples demonstrate how to deploy agents as hosted endpoints in Docker containers.

• Adds agents_in_workflow demo showing concurrent workflow execution
• Adds agent_with_text_search_rag demo showcasing RAG with custom context providers
• Adds agent_with_hosted_mcp demo integrating hosted MCP tools

Reviewed Changes

Copilot reviewed 15 out of 16 changed files in this pull request and generated 3 comments.

File	Description
python/uv.lock	Standard dependency version updates (cachetools, fastapi, huggingface-hub, mcp, mem0ai, openai, openai-agents, openai-chatkit, ruff)
python/samples/demos/hosted_agents/agents_in_workflow/*	New demo: Workflow of concurrent agents (researcher, marketer, legal) with Docker deployment
python/samples/demos/hosted_agents/agent_with_text_search_rag/*	New demo: RAG agent with custom TextSearchContextProvider for customer support with Docker deployment
python/samples/demos/hosted_agents/agent_with_hosted_mcp/*	New demo: Agent with hosted MCP tool for Microsoft Learn documentation with Docker deployment