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/pflag/bool_func.go

@@ -0,0 +1,40 @@
+package pflag
+
+// -- func Value
+type boolfuncValue func(string) error
+
+func (f boolfuncValue) Set(s string) error { return f(s) }
+
+func (f boolfuncValue) Type() string { return "boolfunc" }
+
+func (f boolfuncValue) String() string { return "" } // same behavior as stdlib 'flag' package
+
+func (f boolfuncValue) IsBoolFlag() bool { return true }
+
+// BoolFunc defines a func flag with specified name, callback function and usage string.
+//
+// The callback function will be called every time "--{name}" (or any form that matches the flag) is parsed
+// on the command line.
+func (f *FlagSet) BoolFunc(name string, usage string, fn func(string) error) {
+	f.BoolFuncP(name, "", usage, fn)
+}
+
+// BoolFuncP is like BoolFunc, but accepts a shorthand letter that can be used after a single dash.
+func (f *FlagSet) BoolFuncP(name, shorthand string, usage string, fn func(string) error) {
+	var val Value = boolfuncValue(fn)
+	flag := f.VarPF(val, name, shorthand, usage)
+	flag.NoOptDefVal = "true"
+}
+
+// BoolFunc defines a func flag with specified name, callback function and usage string.
+//
+// The callback function will be called every time "--{name}" (or any form that matches the flag) is parsed
+// on the command line.
+func BoolFunc(name string, usage string, fn func(string) error) {
+	CommandLine.BoolFuncP(name, "", usage, fn)
+}
+
+// BoolFuncP is like BoolFunc, but accepts a shorthand letter that can be used after a single dash.
+func BoolFuncP(name, shorthand string, usage string, fn func(string) error) {
+	CommandLine.BoolFuncP(name, shorthand, usage, fn)
+}