refactor: FeatureFlag.Save and PropertySet.Save lack atomic write

[HeyItsGilbert]

Summary

Both Save methods write directly to the target file with Set-Content. A process crash mid-write leaves a partially written, corrupt file. On shared machines where the flag store is in a common location, there is no integrity guarantee.

Files

• Gatekeeper/Classes/FeatureFlag.ps1:184
• Gatekeeper/Classes/Property.ps1:182

Fix

Write to a temp file then atomically rename:

[void]Save() {
    if ($null -eq $this.FilePath) { throw 'No file path specified to save FeatureFlag.' }
    $tmpPath = "$($this.FilePath).tmp"
    $json = $this | ConvertTo-Json -Depth 10 -EnumsAsStrings
    Set-Content -Path $tmpPath -Value $json
    Move-Item -Path $tmpPath -Destination $this.FilePath -Force
}

Notes

• Found by DualCore (security review)