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/ui/ui.go

@@ -49,9 +49,15 @@ const Marker = "》"
 // It also counts warnings and errors emitted so the caller can summarize at
 // the end of an operation ("Finished successfully." vs "Finished with
 // warnings.").
+//
+// When Quiet is set, Begin/Complete/Info/Notice/Detail/Progress/Banner
+// are silently dropped, but Warning and Error always emit. This honors
+// the convention that --quiet "Suppresses non-error output" — warnings
+// and errors are by definition not suppressible.
 type Writer struct {
 	out      io.Writer
 	color    bool
+	quiet    bool
 	warnings int
 	errors   int
 }
@@ -70,6 +76,13 @@ func NewWithColor(out io.Writer, color bool) *Writer {
 	return &Writer{out: out, color: color}
 }
 
+// SetQuiet toggles the writer's quiet mode. In quiet mode all message
+// classes are silenced except Warning and Error.
+func (w *Writer) SetQuiet(quiet bool) { w.quiet = quiet }
+
+// Quiet reports whether the writer is in quiet mode.
+func (w *Writer) Quiet() bool { return w.quiet }
+
 // Out returns the underlying writer.
 func (w *Writer) Out() io.Writer { return w.out }
 
@@ -100,21 +113,33 @@ func (w *Writer) paint(color, s string) string {
 
 // Begin prints an operation-start line, left-aligned with a white marker.
 func (w *Writer) Begin(format string, args ...any) {
+	if w.quiet {
+		return
+	}
 	w.emit(ansiWhite, Marker, "", format, args)
 }
 
 // Complete prints an operation-completion line in green, left-aligned.
 func (w *Writer) Complete(format string, args ...any) {
+	if w.quiet {
+		return
+	}
 	w.emit(ansiGreen, Marker, ansiGreen, format, args)
 }
 
 // Info prints a neutral status line, left-aligned with a white marker.
 func (w *Writer) Info(format string, args ...any) {
+	if w.quiet {
+		return
+	}
 	w.emit(ansiWhite, Marker, "", format, args)
 }
 
 // Notice prints an attention-worthy informational line, marker in cyan.
 func (w *Writer) Notice(format string, args ...any) {
+	if w.quiet {
+		return
+	}
 	w.emit(ansiCyan, Marker, "", format, args)
 }
 
@@ -139,6 +164,9 @@ func (w *Writer) Error(format string, args ...any) {
 // Distinct from Progress (semantically a "heartbeat") in usage but
 // visually identical.
 func (w *Writer) Detail(format string, args ...any) {
+	if w.quiet {
+		return
+	}
 	w.emit(ansiWhite, "  "+Marker, "", format, args)
 }
 
@@ -150,12 +178,18 @@ func (w *Writer) ErrorCount() int { return w.errors }
 
 // Progress prints an indented heartbeat / per-item update, marker in white.
 func (w *Writer) Progress(format string, args ...any) {
+	if w.quiet {
+		return
+	}
 	w.emit(ansiWhite, "  "+Marker, "", format, args)
 }
 
 // Banner prints a line with no marker, left-aligned. Bold when color
 // is enabled. Used for the application startup banner only.
 func (w *Writer) Banner(format string, args ...any) {
+	if w.quiet {
+		return
+	}
 	body := fmt.Sprintf(format, args...)
 	if w.color {
 		body = ansiBold + body + ansiReset