fix(process): reap entire process group on cmd.Cancel (#39143)

Signed-off-by: Royce Remer <royceremer@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/process/command_windows.go

@@ -0,0 +1,19 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package process
+
+import "os/exec"
+
+// There is no graceful way to kill a process on Windows at the moment
+
+func setSysProcAttribute(cmd *exec.Cmd) {}
+
+func (c *Cmd) onCancel() error {
+	if c.onCancelUserFunc != nil {
+		if err := c.onCancelUserFunc(); err != nil {
+			return err
+		}
+	}
+	return c.Process.Kill()
+}