references across multiple users

src/db/migrations/000014 - reference fix.sql

@@ -0,0 +1,3 @@
+ALTER TABLE public.reference DROP CONSTRAINT reference_uri_key;
+ALTER TABLE public.reference ADD CONSTRAINT uniq__agreement_reference_uri_user_id UNIQUE (uri, user_id);
+CREATE INDEX idx__public__reference__uri ON public.reference (uri);