normalizeVariable function
Parses one raw entry from templateConfig.variables.
Returns null when the entry lacks a valid name.
Implementation
VariableSchema? normalizeVariable(Map<String, dynamic> entry) {
final name = entry['name'] as String?;
if (name == null || name.isEmpty) return null;
final type = entry['type'] == 'number' ? 'number' : 'string';
final fallback =
(entry['fallbackValue'] as String?) ?? (entry['sampleValue'] as String?) ?? '';
return VariableSchema(name: name, type: type, fallbackValue: fallback);
}