fix: resolve mnd and nestif linter errors

- Added constants to replace magic numbers:
  - agePrivKeyPassphraseLength = 64
  - versionNameParts = 2
  - maxVersionsPerDay = 999
- Refactored crypto.go to reduce nesting complexity:
  - Inverted if condition to handle non-existent secret first
  - Extracted getSecretValue helper method

internal/cli/crypto.go

@@ -74,29 +74,7 @@ func (cli *Instance) Encrypt(secretName, inputFile, outputFile string) error {
 		return fmt.Errorf("failed to check if secret exists: %w", err)
 	}
 
-	if exists {
-		// Secret exists, get the age secret key from it
-		var secretValue []byte
-		if os.Getenv(secret.EnvMnemonic) != "" {
-			secretValue, err = secretObj.GetValue(nil)
-		} else {
-			unlocker, unlockErr := vlt.GetCurrentUnlocker()
-			if unlockErr != nil {
-				return fmt.Errorf("failed to get current unlocker: %w", unlockErr)
-			}
-			secretValue, err = secretObj.GetValue(unlocker)
-		}
-		if err != nil {
-			return fmt.Errorf("failed to get secret value: %w", err)
-		}
-
-		ageSecretKey = string(secretValue)
-
-		// Validate that it's a valid age secret key
-		if !isValidAgeSecretKey(ageSecretKey) {
-			return fmt.Errorf("secret '%s' does not contain a valid age secret key", secretName)
-		}
-	} else {
+	if !exists {
 		// Secret doesn't exist, generate new age key and store it
 		identity, err := age.GenerateX25519Identity()
 		if err != nil {
@@ -110,6 +88,19 @@ func (cli *Instance) Encrypt(secretName, inputFile, outputFile string) error {
 		if err != nil {
 			return fmt.Errorf("failed to store age key: %w", err)
 		}
+	} else {
+		// Secret exists, get the age secret key from it
+		secretValue, err := cli.getSecretValue(vlt, secretObj)
+		if err != nil {
+			return fmt.Errorf("failed to get secret value: %w", err)
+		}
+
+		ageSecretKey = string(secretValue)
+
+		// Validate that it's a valid age secret key
+		if !isValidAgeSecretKey(ageSecretKey) {
+			return fmt.Errorf("secret '%s' does not contain a valid age secret key", secretName)
+		}
 	}
 
 	// Parse the secret key
@@ -247,3 +238,17 @@ func isValidAgeSecretKey(key string) bool {
 	_, err := age.ParseX25519Identity(key)
 	return err == nil
 }
+
+// getSecretValue retrieves the value of a secret using the appropriate unlocker
+func (cli *Instance) getSecretValue(vlt *vault.Vault, secretObj *secret.Secret) ([]byte, error) {
+	if os.Getenv(secret.EnvMnemonic) != "" {
+		return secretObj.GetValue(nil)
+	}
+	
+	unlocker, err := vlt.GetCurrentUnlocker()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get current unlocker: %w", err)
+	}
+	
+	return secretObj.GetValue(unlocker)
+}