Class diagrams: #588 can put an association role at the wrong end #589

Round 30 (prod d99eb3c; Sol eval-20261031-054954-wd6o, Sonnet eval-20261031-055114-nyio). Report: frontierclimb .memory/sketchi-loop/r30/REPORT.md.

library-system-class-v2 (Sol) dropped from 3/3 to 3/5 after #588. Two samples fail data-accuracy: the Member-Reservation association places the role "reservations" beside Member instead of Reservation. One fails the class-drawn check "relationship-12 to role". A same-spec replay fb45399 -> d99eb3c changes the scene on exactly those 4 specs (frontierclimb .memory/sketchi-loop/replay/RR30/). #588's attribution placement can move a role or multiplicity to the wrong end. A role/multiplicity label must stay at its own end, not just on its own route. Extend the class-fuzz invariant to check the end as well as the route.