move FactoryState ownership out of BuildingSystem to Simulation

Simulation (and ArenaSimulation in the balancing tool) now owns the factory's
world data; BuildingSystem holds a reference to it. This is what lets the systems
that operate on the data be handed the same state — phase 3's construction and
deconstruction systems, and later the ecs/system/ classes that today take a
BuildingSystem& only to query it.

reset() clears the state alongside m_admin and m_beltSystem, matching how the
subsystems were already rebuilt from scratch.

Falls short of the tick-argument form I sketched: BuildingSystem still reaches
the data through a member reference rather than a parameter. Making it truly
stateless means the const query surface has to find the data some other way, and
that surface is large — findBuilding alone has 64 call sites, with findSite,
getAllBuildings, getAllSites, isTileOccupied and the rest behind it. Doing that
needs a queries facade behind Simulation::getBuildings() so the callers do not
all move, which is its own decision rather than a side effect of this one.

The constructor gains a parameter, so the four owners and the three test fixtures
that build a BuildingSystem directly are updated; the 33 files that only use one
are untouched.

Verified with a golden-checksum capture before and after — all four sample ticks
identical.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YHcUerKAZKWNvSKJxYKbnG

src/balancing/ArenaSimulation.h

@@ -10,6 +10,7 @@
 
 #include "BalancingConfig.h"
 #include "BeltSystem.h"
+#include "FactoryState.h"
 #include "EntityAdmin.h"
 #include "BuildingId.h"
 
@@ -107,6 +108,7 @@ private:
     BuildingId m_nextBuildingId;
 
     EntityAdmin m_admin;
+    FactoryState                      m_factoryState;
     BeltSystem m_beltSystem;
     std::unique_ptr<BuildingSystem> m_buildingSystem;
     std::unique_ptr<ShipSystem>     m_shipSystem;