Print banner before cobra parsing; route arg errors through ui.Error

Two output-style fixes plus a quiet-mode correction.

Banner: a manual scan of os.Args in CLIEntry decides whether to suppress
the banner (--quiet/-q/--cron), then prints it before cobra parses any
arguments. This makes the banner appear even when cobra rejects bad args
("requires at least 2 arg(s)") and on --help — paths that previously
skipped PersistentPreRun entirely. The cobra-side hook plumbing (sync.Once,
PersistentPreRun, custom HelpFunc) is removed.

Errors: rootCmd.SilenceErrors = true so cobra no longer prints its own
"Error: <msg>" line. Any error returned from Execute() goes through
ui.New(os.Stderr).Error(...), giving the documented "🛑 ERROR: <msg>"
format. A new helper cli.ReportError() formats errors from goroutine
paths that can't return through cobra's normal return chain; every
CLI command's fx-goroutine error path now calls it alongside the
existing structured log.Error so both channels record the failure.

Quiet mode: previously --quiet/--cron swapped Vaultik.UI to io.Discard,
which silenced Warning and Error messages too — contradicting the
documented "suppresses non-error output" semantics. ui.Writer now has
a SetQuiet flag that drops Begin/Complete/Info/Notice/Detail/Progress/
Banner only; Warning and Error always emit.

Also folds in restore.go cleanups the audit flagged: the hardcoded
"WARNING:" prefix on the failed-files block now uses ui.Warning +
ui.Detail, the post-restore "Restored N files" line uses ui.Complete,
and the "No files found to restore" branch emits both log.Warn and
ui.Warning so structured logs continue to capture it under --verbose.

internal/cli/root.go

@@ -5,39 +5,11 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
-	"sync"
-	"time"
 
 	"github.com/adrg/xdg"
 	"github.com/spf13/cobra"
-	"sneak.berlin/go/vaultik/internal/globals"
-	"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 {
@@ -61,25 +33,15 @@ func NewRootCommand() *cobra.Command {
 public keys and uploads to S3-compatible storage. No private keys are needed
 on the source system.`,
 		SilenceUsage: true,
-		// 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.
+		// Bare 'vaultik' (no subcommand): print help. The banner is
+		// printed once at process startup by CLIEntry, before cobra
+		// parses arguments, so it appears even when cobra rejects
+		// args (e.g. "requires at least 2 arg(s)") and on --help.
 		Run: func(cmd *cobra.Command, args []string) {
-			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")