Replace symlinks with plain files containing relative paths

- Remove all symlink creation and resolution in favor of plain files
- currentvault file now contains relative path like "vaults.d/default"
- current-unlocker file now contains relative path like "unlockers.d/passphrase"
- current version file now contains relative path like "versions/20231215.001"
- Simplify path resolution to just read file contents and join with parent dir
- Update all tests to read files instead of using os.Readlink

internal/secret/version.go

@@ -4,7 +4,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"log/slog"
-	"os"
 	"path/filepath"
 	"sort"
 	"strings"
@@ -431,59 +430,37 @@ func ListVersions(fs afero.Fs, secretDir string) ([]string, error) {
 	return versions, nil
 }
 
-// GetCurrentVersion returns the version that the "current" symlink points to
+// GetCurrentVersion returns the version that the "current" file points to
 func GetCurrentVersion(fs afero.Fs, secretDir string) (string, error) {
 	currentPath := filepath.Join(secretDir, "current")
 
-	// Try to read as a real symlink first
-	if _, ok := fs.(*afero.OsFs); ok {
-		target, err := os.Readlink(currentPath)
-		if err == nil {
-			// Extract version from path (e.g., "versions/20231215.001" -> "20231215.001")
-			parts := strings.Split(target, "/")
-			if len(parts) >= 2 && parts[0] == "versions" {
-				return parts[1], nil
-			}
-
-			return "", fmt.Errorf("invalid current version symlink format: %s", target)
-		}
-	}
-
-	// Fall back to reading as a file (for MemMapFs testing)
 	fileData, err := afero.ReadFile(fs, currentPath)
 	if err != nil {
-		return "", fmt.Errorf("failed to read current version symlink: %w", err)
+		return "", fmt.Errorf("failed to read current version file: %w", err)
 	}
 
 	target := strings.TrimSpace(string(fileData))
 
-	// Extract version from path
+	// Extract version from path (e.g., "versions/20231215.001" -> "20231215.001")
 	parts := strings.Split(target, "/")
 	if len(parts) >= 2 && parts[0] == "versions" {
 		return parts[1], nil
 	}
 
-	return "", fmt.Errorf("invalid current version symlink format: %s", target)
+	return "", fmt.Errorf("invalid current version file format: %s", target)
 }
 
-// SetCurrentVersion updates the "current" symlink to point to a specific version
+// SetCurrentVersion updates the "current" file to point to a specific version
 func SetCurrentVersion(fs afero.Fs, secretDir string, version string) error {
 	currentPath := filepath.Join(secretDir, "current")
 	targetPath := filepath.Join("versions", version)
 
-	// Remove existing symlink if it exists
+	// Remove existing file if it exists
 	_ = fs.Remove(currentPath)
 
-	// Try to create a real symlink first (works on Unix systems)
-	if _, ok := fs.(*afero.OsFs); ok {
-		if err := os.Symlink(targetPath, currentPath); err == nil {
-			return nil
-		}
-	}
-
-	// Fall back to creating a file with the target path (for MemMapFs testing)
+	// Write the relative path to the file
 	if err := afero.WriteFile(fs, currentPath, []byte(targetPath), FilePerms); err != nil {
-		return fmt.Errorf("failed to create current version symlink: %w", err)
+		return fmt.Errorf("failed to create current version file: %w", err)
 	}
 
 	return nil