Liminalia central spine

liminalia

The tick engine, economy services and emergency dispatch had grown four separate copies of the same wiring. This change puts each in one place.

SimulationServices

A new SimulationServices class owns all 12 tick services: construction (including the shared seed for fires and births), the facade properties the world exposes, and TickAll — the pipeline order (economy, emergency response, life course) that previously lived inline in SimulationWorldTick. The world delegates to it; public API unchanged.

Shared RouteFinder

RouteFinder is stateless Dijkstra but was instantiated six times: the world, fire/crime/health dispatch, labour hiring, and school routing. Now one instance, world.Routes.

Static wage and tax arithmetic

WageService and TaxService are pure arithmetic, like the existing ConstructionCosts precedent. Both are static now. BusinessService, ConsumptionService and PropertyTaxService lost their private copies; LabourCivicStaffing lost an inline new WageService(). Also removed a dead _wageCache field in BusinessService.

ResponderFinder

Fire, crime and health dispatch repeated the same scan verbatim: nearest citizen of a job kind, skipping jailed/travelling/unplaced, routed by pedestrian cost. ResponderFinder.NearestOnDuty is that loop; the three dispatch passes keep only their own bookkeeping.

flake

PartnershipTests.CohabitingPartners_ChildbearingAge_HaveChildrenOverYears flaked once in 15 suite runs — same class as the earlier fire flake. The birth chance is 0.35/year and the test asserted on a decade of unseeded randomness (~3% tail of no child). Seeded with 42; verified deterministic across 10 filtered runs and the full suite.

367 tests pass. Five commits, each independently revertable.