Added support for OpenAI-compatible structured output

internal/validate/standard_validator.go

@@ -108,6 +108,30 @@ func parseJSON(body []byte) (any, error) {
 	return v, nil
 }
 
+func (v *StandardValidator) LoadSchemaDocument(ctx context.Context, schemaPath string) (any, error) {
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	default:
+	}
+
+	resolved, err := v.resolveSchemaPath(schemaPath)
+	if err != nil {
+		return nil, err
+	}
+
+	raw, err := os.ReadFile(resolved)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read schema file %q: %w", resolved, err)
+	}
+
+	var doc any
+	if err := json.Unmarshal(raw, &doc); err != nil {
+		return nil, fmt.Errorf("failed to decode JSON schema %q: %w", resolved, err)
+	}
+	return doc, nil
+}
+
 func (v *StandardValidator) resolveSchemaPath(schemaPath string) (string, error) {
 	if strings.TrimSpace(schemaPath) == "" {
 		return "", errors.New("schema path is required for json_schema validation")