To put it simply — and, yes, gratefully — “Phoenix, Oregon” is the sort of movie a lot of us need right now. It’s an undemandingly enjoyable and reassuringly predictable dramedy in which nothing, not even the sourball attitudes of its comically unpleasant malcontents, ever is allowed to get out of hand or unduly strain credibility. But it also is too playfully spiky and unaffectedly down-to-earth to come across as bland pablum.