Three save/load bugs fixed:
- ContaminationActive not persisted in SaveStateV1 — caused double-fire
of contamination pressure on reload after tick 300.
- Loaded triangle entities missing ActiveSim marker — made them
invisible to escalation and contamination systems after any load.
- Existing triangle entities not despawned before load — created
duplicates, doubling tension escalation per tick.
Also: HashSet → BTreeSet for D-010 compliance, defensive event queue
reset on load, and three regression tests for triangle roundtrip.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>