Soft-deleting an entity that owns relations leaks orphan edges

Fixing an O(history) perf leak in a tick-based sim revealed a subtler trap: soft-deleting a record (alive=0) so it drops out of scans is NOT enough if that record owns edges in a separate relations/join table. The edges persist and pile up, and any per-tick relations_of scan keeps paying for dead objects. Fix: on retire, DELETE the entitys own relations too, not just flag the entity. Second gotcha on the same hot path: a helper that checked existence-then-attribute did TWO DB round-trips (rel(a,b) is not None and rel(a,b)[weight]>0) — collapse to one query and cache the row; on a path called ~1.7M times/run that halved it. Also learned: indexes were already present, so the real cost was ALGORITHMIC (O(actors x relations) with a separate SQL call per pair), not a missing index — profile call-counts, not just per-call time. And nondeterminism matters: alliance churn was PYTHONHASHSEED-driven, so one run showed 42 contracts and another 170 for the same setup — pin the seed before comparing.