Give -v to verbose, move --version to -V (closes #64)

urfave/cli's built-in version flag claimed -v, colliding with the -v
verbose alias on every subcommand, so "mfer -v --version" failed with a
parser error. Verbose is the more common meaning of -v in tools that
offer both, so verbose keeps -v at the root and on every subcommand, and
the version flag takes -V (--version still works).

User-visible change: -v alone now prints help with verbose logging, not
the version; use -V or --version.

The --version flag and the version subcommand share one printer, so
their output is identical. Tests cover -v, --verbose, --version, -V,
-v --version and --verbose --version. The README roadmap item for
--version is checked off.

Model: opus-4-8 (implementation); opus-5-5 (rebase)

internal/cli/mfer.go

@@ -19,6 +19,7 @@ const (
 	cmdCheck    = "check"
 	cmdExport   = "export"
 	cmdFetch    = "fetch"
+	cmdVersion  = "version"
 
 	flagProgress = "progress"
 
@@ -68,6 +69,12 @@ func (mfa *CLIApp) VersionString() string {
 	return mfer.Version
 }
 
+// printVersion writes the version line shared by the --version flag and the
+// version subcommand, so both produce identical output.
+func (mfa *CLIApp) printVersion() {
+	_, _ = fmt.Fprintf(mfa.Stdout, "%s version %s\n", mfa.appname, mfa.VersionString())
+}
+
 func (mfa *CLIApp) printBanner() {
 	if log.GetLevel() <= log.InfoLevel {
 		_, _ = fmt.Fprintln(mfa.Stdout, banner)
@@ -266,10 +273,10 @@ func (mfa *CLIApp) exportCommand() *cli.Command {
 
 func (mfa *CLIApp) versionCommand() *cli.Command {
 	return &cli.Command{
-		Name:  "version",
+		Name:  cmdVersion,
 		Usage: "Show version",
 		Action: func(_ *cli.Context) error {
-			_, _ = fmt.Fprintln(mfa.Stdout, mfa.VersionString())
+			mfa.printVersion()
 
 			return nil
 		},
@@ -325,6 +332,20 @@ func (mfa *CLIApp) run(args []string) {
 	log.SetOutput(mfa.Stdout, mfa.Stderr)
 	log.Init()
 
+	// -v means verbose, not version. urfave/cli's built-in version flag
+	// claims -v by default, colliding with the -v verbose alias used here and
+	// on every subcommand; that collision makes "mfer -v --version" fail to
+	// parse. Verbose is the more common meaning of -v in tools that offer
+	// both, so verbose keeps -v and the version flag takes the capital -V.
+	// VersionFlag and VersionPrinter are urfave/cli package globals; run() is
+	// serialized in tests, so assigning them here is safe.
+	cli.VersionFlag = &cli.BoolFlag{
+		Name:    cmdVersion,
+		Aliases: []string{"V"},
+		Usage:   "print the version",
+	}
+	cli.VersionPrinter = func(_ *cli.Context) { mfa.printVersion() }
+
 	mfa.app = &cli.App{
 		Name:                 mfa.appname,
 		Usage:                "Manifest generator",
@@ -332,11 +353,13 @@ func (mfa *CLIApp) run(args []string) {
 		EnableBashCompletion: true,
 		Writer:               mfa.Stdout,
 		ErrWriter:            mfa.Stderr,
+		Flags:                commonFlags(),
 		Action: func(c *cli.Context) error {
 			if c.Args().Len() > 0 {
 				return fmt.Errorf("%w %q", errUnknownCommand, c.Args().First())
 			}
 
+			mfa.setVerbosity(c)
 			mfa.printBanner()
 
 			return cli.ShowAppHelp(c)