Proposed zoning changes that could expand several mixed residential-commercial corridors in the Heights have touched off a debate between pro- and anti-development neighbors and the city over the future of the neighborhood. Zoning amendments sponsored by the city planning staff would zone parts of Kennedy Boulevard and Summit Avenue, among other places in the Heights, as residential-commercial districts, making it easier to add ground-floor retail businesses. Some ground floor retail already exists side-by-side with houses on those corridors, which are technically zoned to be residential neigh…