Fix 'secret get' to output to stdout instead of stderr

- Add Print method to CLI Instance that uses cmd.OutOrStdout()
- Update GetSecretWithVersion to use cli.Print instead of cmd.Print
- Add test to verify secret values go to stdout, not stderr
- Store command reference in Instance for proper output handling

internal/cli/stdout_stderr_test.go

@@ -0,0 +1,72 @@
+package cli_test
+
+import (
+	"bytes"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// TestGetCommandOutputsToStdout tests that 'secret get' outputs the secret value to stdout, not stderr
+func TestGetCommandOutputsToStdout(t *testing.T) {
+	// Create a temporary directory for our vault
+	tempDir := t.TempDir()
+
+	// Set environment variables for the test
+	t.Setenv("SB_SECRET_STATE_DIR", tempDir)
+
+	// Find the secret binary path
+	wd, err := filepath.Abs("../..")
+	require.NoError(t, err, "should get working directory")
+	secretPath := filepath.Join(wd, "secret")
+
+	testMnemonic := "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about"
+	testPassphrase := "test-passphrase"
+
+	// Initialize vault
+	cmd := exec.Command(secretPath, "init")
+	cmd.Env = []string{
+		"SB_SECRET_STATE_DIR=" + tempDir,
+		"SB_SECRET_MNEMONIC=" + testMnemonic,
+		"SB_UNLOCK_PASSPHRASE=" + testPassphrase,
+		"PATH=" + "/usr/bin:/bin",
+	}
+	output, err := cmd.CombinedOutput()
+	require.NoError(t, err, "init should succeed: %s", string(output))
+
+	// Add a secret
+	cmd = exec.Command(secretPath, "add", "test/secret")
+	cmd.Env = []string{
+		"SB_SECRET_STATE_DIR=" + tempDir,
+		"SB_SECRET_MNEMONIC=" + testMnemonic,
+		"PATH=" + "/usr/bin:/bin",
+	}
+	cmd.Stdin = strings.NewReader("test-secret-value")
+	output, err = cmd.CombinedOutput()
+	require.NoError(t, err, "add should succeed: %s", string(output))
+
+	// Test that 'secret get' outputs to stdout, not stderr
+	cmd = exec.Command(secretPath, "get", "test/secret")
+	cmd.Env = []string{
+		"SB_SECRET_STATE_DIR=" + tempDir,
+		"SB_SECRET_MNEMONIC=" + testMnemonic,
+		"PATH=" + "/usr/bin:/bin",
+	}
+
+	var stdout, stderr bytes.Buffer
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+
+	err = cmd.Run()
+	require.NoError(t, err, "get should succeed")
+
+	// The secret value should be in stdout
+	assert.Equal(t, "test-secret-value", strings.TrimSpace(stdout.String()), "secret value should be in stdout")
+
+	// Nothing should be in stderr
+	assert.Empty(t, stderr.String(), "stderr should be empty")
+}