Shares of RH fell after hours on Wednesday after the luxury furniture chain forecast full-year and first-quarter sales that came in below expectations, saying a housing-market slump and recent tremors in the nation’s banking system would weigh on its wealthier customers in the months to come. The company said it expected full-year sales in the range of $2.9 billion to $3.1 billion, compared with FactSet forecasts for $3.44 billion. For the first quarter, RH forecast sales of $720 million to $735 million. Wall Street was expecting…