fix(stdio): always set windowsHide on Windows, not just in Electron

.changeset/fix-stdio-windows-hide.md

@@ -0,0 +1,5 @@
+---
+'@modelcontextprotocol/sdk': patch
+---
+
+Always set windowsHide to true when spawning stdio server processes on Windows, not just in Electron environments.

src/client/stdio.ts

@@ -125,7 +125,9 @@ export class StdioClientTransport implements Transport {
                 },
                 stdio: ['pipe', 'pipe', this._serverParams.stderr ?? 'inherit'],
                 shell: false,
-                windowsHide: process.platform === 'win32' && isElectron(),
+                // Always hide the console window on Windows, not just in Electron.
+                // The option is a no-op on other platforms.
+                windowsHide: true,
                 cwd: this._serverParams.cwd
             });
 
@@ -257,7 +259,3 @@ export class StdioClientTransport implements Transport {
         });
     }
 }
-
-function isElectron() {
-    return 'type' in process;
-}