fix: resolve exported type stuttering issues (revive)

- Rename VaultMetadata to Metadata in internal/vault package to avoid stuttering
- Rename BIP85DRNG to DRNG in pkg/bip85 package to avoid stuttering
- Update all references in code and tests

internal/vault/management.go

@@ -26,6 +26,7 @@ func isValidVaultName(name string) bool {
 		return false
 	}
 	matched, _ := regexp.MatchString(`^[a-z0-9\.\-\_]+$`, name)
+
 	return matched
 }
 
@@ -85,6 +86,7 @@ func ResolveVaultSymlink(fs afero.Fs, symlinkPath string) (string, error) {
 			}
 
 			secret.Debug("resolveVaultSymlink completed successfully", "result", target)
+
 			return target, nil
 		}
 	}
@@ -102,6 +104,7 @@ func ResolveVaultSymlink(fs afero.Fs, symlinkPath string) (string, error) {
 	secret.Debug("Read target path from file", "target", target)
 
 	secret.Debug("resolveVaultSymlink completed via fallback", "result", target)
+
 	return target, nil
 }
 
@@ -250,7 +253,7 @@ func CreateVault(fs afero.Fs, stateDir string, name string) (*Vault, error) {
 	}
 
 	// Save vault metadata
-	metadata := &VaultMetadata{
+	metadata := &Metadata{
 		CreatedAt:          time.Now(),
 		DerivationIndex:    derivationIndex,
 		PublicKeyHash:      publicKeyHash,
@@ -268,6 +271,7 @@ func CreateVault(fs afero.Fs, stateDir string, name string) (*Vault, error) {
 
 	// Create and return the vault
 	secret.Debug("Successfully created vault", "name", name)
+
 	return NewVault(fs, stateDir, name), nil
 }
 
@@ -321,5 +325,6 @@ func SelectVault(fs afero.Fs, stateDir string, name string) error {
 	}
 
 	secret.Debug("Successfully selected vault", "vault_name", name)
+
 	return nil
 }