setCustom method
Sets and persists the custom cols×rows, clamped to the valid range.
Implementation
void setCustom(int cols, int rows) {
final c = cols.clamp(kMinCols, kMaxCols);
final r = rows.clamp(kMinRows, kMaxRows);
customCols.value = c;
customRows.value = r;
_settings.terminalCustomCols = c;
_settings.terminalCustomRows = r;
}