## Summary
This PR adds a new detection rule for AWS CloudShell environment creation, based on the **T1059.009 - Command and Scripting Interpreter: Cloud API** technique as documented in the [AWS Threat Technique Catalog](https://aws-samples.github.io/threat-technique-catalog-for-aws/Techniques/T1059.009.html).
AWS CloudShell is a browser-based shell that provides command-line access to AWS resources directly from the AWS Management Console. While convenient for administrators, CloudShell can be abused by adversaries who gain access to compromised console sessions to execute commands, install tools, or interact with AWS services without needing local CLI credentials.
This rule detects the `CreateEnvironment` API call, which occurs when:
- A user launches CloudShell for the **first time**
- A user accesses CloudShell in a **new AWS region** (each region maintains a separate environment)
### Why `CreateEnvironment` instead of `CreateSession`?
`
While both `CreateEnviroment` and `CreateSession` are noted in the catalog for this technique, during testing I observed that:
- **`CreateEnvironment`** is called when a new CloudShell environment is created (first-time user OR new region)
- **`CreateSession`** is called when reconnecting to an existing CloudShell environment that was previously created
By focusing on `CreateEnvironment`, we capture the meaningful signal (new environment creation) while avoiding noise from users simply reconnecting to existing sessions.
Isai