035-workspaces-personal: requires AD directory user for non-interactive testing

## Problem
The WorkSpaces tutorial requires a user to exist in the Active Directory before creating a WorkSpace. Simple AD user creation needs LDAP tools or a domain-joined EC2 instance.

## Current state
- Simple AD directory deployed via `000-prereqs-directory` CFN stack
- Directory registered with WorkSpaces
- Script finds the directory but fails because the auto-generated username doesn't exist in AD

## Steps to resolve
1. Launch a domain-joined EC2 instance in the directory's VPC
2. Use AD tools to create a test user
3. Or: modify the script to use the WorkSpaces API to create a user (if supported)
4. Test the script end-to-end
5. Add back to the non-interactive PR

Start with the script for 035-workspaces-personal and the 000-prereqs-directory CloudFormation stack, confirming how the directory is found and where the generated username is used. Check whether the WorkSpaces API supports user creation; otherwise use a domain-joined EC2 instance and AD tools. Done means the script runs end-to-end and is restored to the non-interactive PR.

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