Print startup banner on every invocation (except -q / --cron)

Adds maybePrintBanner() called from three cobra hooks:
  - PersistentPreRun on root: covers every subcommand invocation
  - Custom HelpFunc on root: covers --help and group-level help
  - Run on root: covers bare 'vaultik' with no subcommand

bannerOnce sync.Once ensures the banner prints exactly once per
process regardless of which hook(s) fire.

Removed the duplicate banner-print from fx setupGlobals; that hook
still handles the --cron/--quiet UI swap for the rest of the output.

internal/cli/app.go

@@ -35,18 +35,16 @@ type AppOptions struct {
 	Invokes    []fx.Option
 }
 
-// setupGlobals records the startup time and prints the startup banner.
-// In --cron mode the banner is suppressed (LogOptions.Cron == true).
+// setupGlobals records the startup time and, when an output-suppression
+// flag is active, replaces the UI writer with a discarding one so no
+// user-facing output is emitted. The startup banner itself is printed
+// by the root command's PersistentPreRun (see maybePrintBanner).
 func setupGlobals(lc fx.Lifecycle, g *globals.Globals, v *vaultik.Vaultik, opts log.LogOptions) {
 	lc.Append(fx.Hook{
 		OnStart: func(ctx context.Context) error {
 			g.StartTime = time.Now().UTC()
 			if opts.Cron || opts.Quiet {
-				// Replace UI writer with a discarding one so all
-				// user-facing output is suppressed.
 				v.UI = ui.NewWithColor(io.Discard, false)
-			} else {
-				writeStartupBanner(v.UI, g.StartTime, g.ShortCommit())
 			}
 			return nil
 		},

internal/cli/root.go

@@ -5,6 +5,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/adrg/xdg"
@@ -13,6 +14,30 @@ import (
 	"sneak.berlin/go/vaultik/internal/ui"
 )
 
+// bannerOnce ensures the banner is printed at most once per process,
+// even if multiple cobra hooks (PersistentPreRun, Help, Run) would
+// otherwise each call maybePrintBanner.
+var bannerOnce sync.Once
+
+// maybePrintBanner prints the application banner unless an output-
+// suppression flag is active. Safe to call multiple times — it prints
+// at most once per process.
+func maybePrintBanner(cmd *cobra.Command) {
+	if rootFlags.Quiet {
+		return
+	}
+	if cronFlag := cmd.Flags().Lookup("cron"); cronFlag != nil && cronFlag.Value.String() == "true" {
+		return
+	}
+	bannerOnce.Do(func() {
+		short := globals.Commit
+		if len(short) > 12 {
+			short = short[:12]
+		}
+		writeStartupBanner(ui.New(os.Stdout), time.Now().UTC(), short)
+	})
+}
+
 // RootFlags holds global flags that apply to all commands.
 // These flags are defined on the root command and inherited by all subcommands.
 type RootFlags struct {
@@ -35,20 +60,25 @@ func NewRootCommand() *cobra.Command {
 public keys and uploads to S3-compatible storage. No private keys are needed
 on the source system.`,
 		SilenceUsage: true,
-		// When invoked with no subcommand, print the banner then the
-		// usage/help. Cobra's default behavior (without a Run) just
-		// prints help, which skips the banner.
+		// Banner before every subcommand invocation that doesn't
+		// suppress output. fx setupGlobals will not print it again.
+		PersistentPreRun: func(cmd *cobra.Command, args []string) {
+			maybePrintBanner(cmd)
+		},
+		// Bare 'vaultik' (no subcommand): banner + help.
 		Run: func(cmd *cobra.Command, args []string) {
-			startTime := time.Now().UTC()
-			short := globals.Commit
-			if len(short) > 12 {
-				short = short[:12]
-			}
-			writeStartupBanner(ui.New(os.Stdout), startTime, short)
+			maybePrintBanner(cmd)
 			_ = cmd.Help()
 		},
 	}
 
+	// Help output (--help and group-level cmds) also gets the banner.
+	defaultHelp := cmd.HelpFunc()
+	cmd.SetHelpFunc(func(c *cobra.Command, args []string) {
+		maybePrintBanner(c)
+		defaultHelp(c, args)
+	})
+
 	// Add global flags
 	cmd.PersistentFlags().StringVar(&rootFlags.ConfigPath, "config", "", "Path to config file (default: $VAULTIK_CONFIG or platform config dir)")
 	cmd.PersistentFlags().BoolVarP(&rootFlags.Verbose, "verbose", "v", false, "Enable verbose output")