Support AWS profiles for deployment (e.g. `agentcore deploy --profile xxx`)

## Summary

Customers want to be able to **use AWS profiles for deployment**, e.g. `agentcore deploy --profile xxx`.

## Problem

- There's no way to select a specific AWS profile when deploying.
- Users working across multiple accounts/profiles can't easily target the intended one for a deployment.

## Desired behavior

- Add a `--profile` option (e.g. `agentcore deploy --profile xxx`) that uses the specified AWS profile for the deployment.

## Environment

- CLI version: `0.22.0`
- User agent: `AgentCoreCLI/0.22.0 (darwin 25.3.0; node/v24.18.0)`
- OS: `darwin 25.3.0`
- Node: `v24.18.0`

Start at the `agentcore deploy` CLI entry point and trace how deployment credentials are selected. Add the requested `--profile` option and verify that `agentcore deploy --profile xxx` uses the specified AWS profile without changing the default behavior.

Written by the indexing model from the issue text.