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/unlockers.go

@@ -39,7 +39,8 @@ func (v *Vault) GetCurrentUnlocker() (secret.Unlocker, error) {
 		// Try to read as symlink first
 		unlockerDir, err = linkReader.ReadlinkIfPossible(currentUnlockerPath)
 		if err != nil {
-			secret.Debug("Failed to read symlink, falling back to file contents", "error", err, "symlink_path", currentUnlockerPath)
+			secret.Debug("Failed to read symlink, falling back to file contents",
+				"error", err, "symlink_path", currentUnlockerPath)
 			// Fallback: read the path from file contents
 			unlockerDirBytes, err := afero.ReadFile(v.fs, currentUnlockerPath)
 			if err != nil {
@@ -363,7 +364,9 @@ func (v *Vault) CreatePassphraseUnlocker(passphrase string) (*secret.PassphraseU
 
 	// Write public key
 	pubKeyPath := filepath.Join(unlockerDir, "pub.age")
-	if err := afero.WriteFile(v.fs, pubKeyPath, []byte(unlockerIdentity.Recipient().String()), secret.FilePerms); err != nil {
+	if err := afero.WriteFile(v.fs, pubKeyPath,
+		[]byte(unlockerIdentity.Recipient().String()),
+		secret.FilePerms); err != nil {
 		return nil, fmt.Errorf("failed to write unlocker public key: %w", err)
 	}