fix: write JSON config without UTF-8 BOM on Windows

PowerShell's Set-Content -Encoding UTF8 adds a Byte Order Mark (BOM)
at the start of the file. Claude Desktop's JSON parser rejects BOM,
causing "Unexpected token" error on startup.

Fixed by using .NET's WriteAllText() which writes UTF-8 without BOM.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: julienld

scripts/install-windows.ps1

@@ -98,11 +98,13 @@ if (Test-Path $ConfigFile) {
 
     # For simplicity, we write the clean config (merging would require complex JSON handling)
     # The backup preserves any other MCP servers the user had
-    $JsonConfig | Set-Content $ConfigFile -Encoding UTF8
+    # Use .NET to write UTF-8 without BOM (PowerShell's -Encoding UTF8 adds BOM which breaks JSON parsers)
+    [System.IO.File]::WriteAllText($ConfigFile, $JsonConfig)
     Write-Host "  Configuration updated successfully" -ForegroundColor White
 } else {
     # Create new config file
-    $JsonConfig | Set-Content $ConfigFile -Encoding UTF8
+    # Use .NET to write UTF-8 without BOM (PowerShell's -Encoding UTF8 adds BOM which breaks JSON parsers)
+    [System.IO.File]::WriteAllText($ConfigFile, $JsonConfig)
     Write-Host "  Created new configuration file" -ForegroundColor White
 }
 Write-Host "  Claude Desktop configured" -ForegroundColor Green