Oregon Nurses Association members say they will continue their picket at six Providence facilities across Oregon, including Hood River, Friday and Saturday in response to what they term an unlawful lockout of nurses after their three-day strike.  Picketing was to wrap up Thursday, and the ONA says it had indicated that nurses would unconditionally offer to return to work Friday morning.  But the ONA claims Providence announced that it would only welcome nurses back to their regular shifts starting Sunday morning.  Providence hired replacement nurses on five-day contracts, and KOIN-TV reports Providence has since said it was going to notify nurses whether they would be selected to fulfill their shifts via phone calls Thursday evening.  The ONA says that constitutes an unlawful partial lockout, and is filing an unfair labor practice charge, and will also seek back pay for all affected nurses.  Nurses have been in contract talks with Providence for a number of months, with staffing levels emerging as the major stumbling block.