Login Application: Add PowerShell Option for Copying AWS Credential Env Vars

**Describe the issue**
Currently the login application has a button called "Click for Credentials" but only comes in the form of Linux based "export" commands. A team that we recently onboarded uses PowerShell and was unable to easily copy the AWS credentials. They had to manually change each export command.

**Additional context**
- These credentials expire every hour or so, and having to change them every time would quickly become laborious
- There could be other common "export" equivalents that we may want to explore

**Definition of done**
- have an option to copy env vars in PowerShell compatible "$env:"

Start at the login application entry point that implements the “Click for Credentials” button and trace how it generates the current Linux export commands. Add an option for PowerShell-compatible $env: commands, then verify that copying credentials produces the requested format. The issue does not name a file or test, so locate the existing credential-copying behavior first.

Written by the indexing model from the issue text.