fix: resolve all nlreturn linter errors

Add blank lines before return statements in all files to satisfy
the nlreturn linter. This improves code readability by providing
visual separation before return statements.

Changes made across 24 files:
- internal/cli/*.go
- internal/secret/*.go
- internal/vault/*.go
- pkg/agehd/agehd.go
- pkg/bip85/bip85.go

All 143 nlreturn issues have been resolved.

internal/cli/vault.go

@@ -55,6 +55,7 @@ func newVaultCreateCmd() *cobra.Command {
 		Args:  cobra.ExactArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			cli := NewCLIInstance()
+
 			return cli.CreateVault(cmd, args[0])
 		},
 	}
@@ -67,6 +68,7 @@ func newVaultSelectCmd() *cobra.Command {
 		Args:  cobra.ExactArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			cli := NewCLIInstance()
+
 			return cli.SelectVault(cmd, args[0])
 		},
 	}
@@ -209,6 +211,7 @@ func (cli *Instance) VaultImport(cmd *cobra.Command, vaultName string) error {
 	derivationIndex, err := vault.GetNextDerivationIndex(cli.fs, cli.stateDir, mnemonic)
 	if err != nil {
 		secret.Debug("Failed to get next derivation index", "error", err)
+
 		return fmt.Errorf("failed to get next derivation index: %w", err)
 	}
 	secret.Debug("Using derivation index", "index", derivationIndex)
@@ -256,6 +259,7 @@ func (cli *Instance) VaultImport(cmd *cobra.Command, vaultName string) error {
 
 	if err := vault.SaveVaultMetadata(cli.fs, vaultDir, existingMetadata); err != nil {
 		secret.Debug("Failed to save vault metadata", "error", err)
+
 		return fmt.Errorf("failed to save vault metadata: %w", err)
 	}
 	secret.Debug("Saved vault metadata with derivation index and public key hash")
@@ -276,6 +280,7 @@ func (cli *Instance) VaultImport(cmd *cobra.Command, vaultName string) error {
 	passphraseUnlocker, err := vlt.CreatePassphraseUnlocker(passphraseStr)
 	if err != nil {
 		secret.Debug("Failed to create unlocker", "error", err)
+
 		return fmt.Errorf("failed to create unlocker: %w", err)
 	}