PITTSFIELD, MASS. — Pittsfield-based toy retailer KB Toys has filed for Chapter 11 bankruptcy. The chain intends to liquidate all of its stores, and has begun going-out-of-business sales to capitalize on the last two weeks of the holiday shopping season. This marks the second time the retailer has filed for bankruptcy in the past 4 years. KB Toys filed for Chapter 11 bankruptcy in 2004, and emerged in 2005 when it was purchased by Prentice Capital Management LP.