Add Windows CI coverage for JSON remediation

[nshkrdotcom]

Summary

The CRLF regression slipped through because our test suite and CI only run in Unix environments. Even after adding the Windows-style sample to the tests, we still rely on Linux runners, so we do not exercise the code path on Windows itself.

Proposed Fix

Add a Windows job (PowerShell) to the CI matrix that installs Erlang/OTP and Elixir, runs mix deps.get, and executes the existing test suite. Document the setup steps so contributors can reproduce locally if needed.

Benefits

• Catches Windows-specific newline or filesystem issues before release
• Gives us confidence when users report regressions from Windows environments
• Provides a reference environment for future debugging of platform differences