mciasctl: convert from flag to cobra

Adds shell completion support (zsh, bash, fish) via cobra's built-in
completion command. All existing behavior and security measures are
preserved.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vendor/github.com/spf13/cobra/command_win.go

@@ -0,0 +1,41 @@
+// Copyright 2013-2023 The Cobra Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build windows
+// +build windows
+
+package cobra
+
+import (
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/inconshreveable/mousetrap"
+)
+
+var preExecHookFn = preExecHook
+
+func preExecHook(c *Command) {
+	if MousetrapHelpText != "" && mousetrap.StartedByExplorer() {
+		c.Print(MousetrapHelpText)
+		if MousetrapDisplayDuration > 0 {
+			time.Sleep(MousetrapDisplayDuration)
+		} else {
+			c.Println("Press return to continue...")
+			fmt.Scanln()
+		}
+		os.Exit(1)
+	}
+}