03-integrations-AWS-API-MCP

## Summary

In this PR, I added a sample that integrates the [AWS API MCP Server](https://github.com/awslabs/mcp/tree/main/src/aws-api-mcp-server) with Amazon Bedrock AgentCore using the Strands framework.

## What's Included
- Strands agent that runs AWS API MCP Server as a subprocess
- Complete setup documentation with credential configuration options

Start with the AWS API MCP Server documentation linked in the issue and review the existing agentcore-samples layout to identify where this sample belongs. The issue describes a Strands agent using the server as a subprocess and requires setup documentation covering credential configuration; done means both the runnable sample and that documentation are included.

Written by the indexing model from the issue text.