fix: resolve mnd and nestif linter errors

- Define base85 constants (base85ChunkSize, base85DigitCount, base85Base)
- Replace magic numbers in base85 encoding logic with named constants
- Add nolint:nestif comments for legitimate nested conditionals:
  - crypto.go: Clear separation between secret generation vs retrieval
  - secrets.go: Separate JSON and table output formatting logic
  - vault.go: Separate JSON and text output formatting logic

internal/cli/vault.go

@@ -98,7 +98,7 @@ func (cli *Instance) ListVaults(cmd *cobra.Command, jsonOutput bool) error {
 		return err
 	}
 
-	if jsonOutput {
+	if jsonOutput { //nolint:nestif // Separate JSON and text output formatting logic
 		// Get current vault name for context
 		currentVault := ""
 		if currentVlt, err := vault.GetCurrentVault(cli.fs, cli.stateDir); err == nil {