fix: set USERPROFILE on Windows in config_fresh tests

[svarlamov]

Root cause

PR #930 added tests/config_fresh_test.rs, which redirects the home directory during each test by setting the HOME env var to a TempDir. This works on Linux/macOS, but on Windows home_dir() (src/mdm/utils.rs) reads USERPROFILE before HOME:

// src/mdm/utils.rs
#[cfg(windows)]
if let Ok(userprofile) = std::env::var("USERPROFILE") ... {
    return PathBuf::from(userprofile);  // always wins on Windows CI
}
// HOME is only reached if USERPROFILE is unset

So on Windows CI USERPROFILE is always set (e.g. C:\Users\runneradmin), meaning:

• save_file_config() wrote the config to the real user profile directory
• The test then asserted the file existed under temp_dir/.git-ai/config.json — which never got created
• All 7 tests in the suite (3 Windows jobs × 7 tests) panicked with Config file should exist

Fix

Introduce a HomeEnvGuard RAII helper that saves and restores HOME on all platforms, plus USERPROFILE/HOMEDRIVE/HOMEPATH on Windows. It clears HOMEDRIVE/HOMEPATH so the USERPROFILE branch in home_dir() is taken exclusively and points at the temp dir. Every test is updated to use _home_guard = HomeEnvGuard::set(temp_dir.path()) instead of the open-coded save/restore blocks.

All 7 tests pass locally (Linux). The Windows-specific guard code compiles only under #[cfg(windows)].

Test plan

• All 3 Windows CI jobs (wrapper, wrapper-daemon, daemon) pass config_fresh_test
• No Linux/macOS regressions (cargo test --test config_fresh_test passes: 7/7 ✓)

🤖 Generated with Claude Code

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[devin-ai-integration]

✅ Devin Review: No Issues Found

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