The Chicago Housing Authority hired an architecture firm to rehabilitate seven buildings for compliance with federal handicap-accessibility laws.But after that firm’s work was complete, the CHA needed to spend another $4.3 million retrofitting the work before it could find itself in federal regulators’ good graces.This month, a state appeals panel ruled breach-of-contract or indemnity claims against the architect would run afoul of federal law that discourages property owners from discriminating against tenants …