fix: JSON validation accepts @placeholders@ as valid values

src/componets/content/ConfigTemplate.tsx

@@ -51,7 +51,9 @@ export function ConfigTemplate(props: ConfigTemplateProps) {
     // Validate JSON on every change
     try {
       if (value.trim()) {
-        JSON.parse(value);
+        // Replace @placeholders@ with valid JSON values for validation
+        const sanitizedValue = value.replace(/"@?(\w+)@?"/g, '"__PLACEHOLDER__"');
+        JSON.parse(sanitizedValue);
         setJsonError(null);
       } else {
         setJsonError(null);