Update aws-agentcore power to support new agentcore-cli

[wilmatos]

Overview

The current aws-agentcore power references the older agentcore CLI. We need to update the power definition to support the new agentcore-cli from https://github.com/aws/agentcore-cli.

Current State

The POWER.md and steering files currently reference the legacy agentcore CLI commands and workflows.

Required Changes

• Review new agentcore-cli API and command structure from https://github.com/aws/agentcore-cli
• Update POWER.md documentation to reflect new CLI commands and workflows
• Update steering files (getting-started.md, agentcore-gateway-integration.md, agentcore-memory-integration.md) with new CLI usage patterns
• Update MCP tool descriptions and examples to align with new CLI
• Test all documented workflows with the new agentcore-cli
• Update troubleshooting section with new CLI-specific issues and solutions

Acceptance Criteria

• All steering files reference the new agentcore-cli
• MCP tool documentation is accurate for the new CLI
• Examples in POWER.md work with the new agentcore-cli
• Troubleshooting section covers new CLI-specific scenarios

Related Resources

• New agentcore-cli: https://github.com/aws/agentcore-cli
• Current power: aws-agentcore/POWER.md