fix: add missing printfStdout, printlnStdout, scanlnStdin, FetchBlob, and FetchAndDecryptBlob methods

These methods were referenced in main but never defined, causing compilation
failures. They were introduced by merges that assumed dependent PRs were
already merged.

internal/vaultik/vaultik.go

@@ -135,6 +135,34 @@ func (v *Vaultik) Outputf(format string, args ...any) {
 	_, _ = fmt.Fprintf(v.Stdout, format, args...)
 }
 
+// printfStdout writes formatted output to stdout.
+func (v *Vaultik) printfStdout(format string, args ...any) {
+	_, _ = fmt.Fprintf(v.Stdout, format, args...)
+}
+
+// printlnStdout writes a line to stdout.
+func (v *Vaultik) printlnStdout(args ...any) {
+	_, _ = fmt.Fprintln(v.Stdout, args...)
+}
+
+// scanlnStdin reads a line from stdin into the provided string pointer.
+func (v *Vaultik) scanlnStdin(s *string) error {
+	_, err := fmt.Fscanln(v.Stdin, s)
+	return err
+}
+
+// FetchBlob downloads a blob from storage and returns a reader for the encrypted data.
+func (v *Vaultik) FetchBlob(ctx context.Context, blobHash string, expectedSize int64) (io.ReadCloser, int64, error) {
+	blobPath := fmt.Sprintf("blobs/%s/%s/%s", blobHash[:2], blobHash[2:4], blobHash)
+
+	reader, err := v.Storage.Get(ctx, blobPath)
+	if err != nil {
+		return nil, 0, fmt.Errorf("downloading blob: %w", err)
+	}
+
+	return reader, expectedSize, nil
+}
+
 // TestVaultik wraps a Vaultik with captured stdout/stderr for testing
 type TestVaultik struct {
 	*Vaultik