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/lib/sim/BuildingSystem.cpp

@@ -23,6 +23,7 @@ bool inputLaneEntryFree(const std::vector<BeltItemSlot>& lane)
 }  // namespace
 
 BuildingSystem::BuildingSystem(const GameConfig& config,
+                               FactoryState& state,
                                BeltSystem& belts,
                                std::function<BuildingId()> allocateBuildingId,
                                std::function<void(int)> addBuildingBlocks,
@@ -31,6 +32,7 @@ BuildingSystem::BuildingSystem(const GameConfig& config,
                                std::function<bool(const std::string&)> isItemUnlocked,
                                std::mt19937& rng)
     : m_config(config)
+    , m_state(state)
     , m_belts(belts)
     , m_allocateBuildingId(std::move(allocateBuildingId))
     , m_addBuildingBlocks(std::move(addBuildingBlocks))