fix(windows): add windowsHide to detached spawn calls to suppress console windows (#44693)

The restart helper and taskkill spawn calls were missing windowsHide: true,
causing visible command prompt windows to flash on screen during gateway
restart and process cleanup on Windows.

src/cli/update-cli/restart-helper.test.ts

@@ -287,6 +287,7 @@ describe("restart-helper", () => {
       expect(spawn).toHaveBeenCalledWith("/bin/sh", [scriptPath], {
         detached: true,
         stdio: "ignore",
+        windowsHide: true,
       });
       expect(mockChild.unref).toHaveBeenCalled();
     });
@@ -302,6 +303,7 @@ describe("restart-helper", () => {
       expect(spawn).toHaveBeenCalledWith("cmd.exe", ["/d", "/s", "/c", scriptPath], {
         detached: true,
         stdio: "ignore",
+        windowsHide: true,
       });
       expect(mockChild.unref).toHaveBeenCalled();
     });
@@ -317,6 +319,7 @@ describe("restart-helper", () => {
       expect(spawn).toHaveBeenCalledWith("cmd.exe", ["/d", "/s", "/c", `"${scriptPath}"`], {
         detached: true,
         stdio: "ignore",
+        windowsHide: true,
       });
     });
   });

src/cli/update-cli/restart-helper.ts

@@ -169,6 +169,7 @@ export async function runRestartScript(scriptPath: string): Promise<void> {
   const child = spawn(file, args, {
     detached: true,
     stdio: "ignore",
+    windowsHide: true,
   });
   child.unref();
 }

src/process/kill-tree.ts

@@ -83,6 +83,7 @@ function runTaskkill(args: string[]): void {
     spawn("taskkill", args, {
       stdio: "ignore",
       detached: true,
+      windowsHide: true,
     });
   } catch {
     // Ignore taskkill spawn failures