OLYMPIA, Wash. — For the past 10 years, Dominique Horn has worked for a community health organization in the fast-growing city of Vancouver in Washington state, helping people squeezed by soaring rents to try to avoid homelessness. Sometimes she wonders if she’s going to be her agency’s next client. With her husband struggling at times to find work, Horn has maxed out her credit cards to keep pace with the rent. She has relied on public assistance and stayed in shelters. The couple and their two