Make cross-configuration validation deterministic

internal/config/validate_helpers.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"path/filepath"
 	"regexp"
+	"sort"
 	"strings"
 	"time"
 )
@@ -11,6 +12,15 @@ import (
 var windowsAbsPathRE = regexp.MustCompile(`^[A-Za-z]:[\\/].*`)
 var envVarNameRE = regexp.MustCompile(`^[A-Za-z_][A-Za-z0-9_]*$`)
 
+func sortedStringKeys[V any](values map[string]V) []string {
+	keys := make([]string, 0, len(values))
+	for key := range values {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+	return keys
+}
+
 func validateEnvVarNameField(fieldName, value string) error {
 	trimmed := strings.TrimSpace(value)
 	if trimmed == "" {