move ecs related code to own folder

src/lib/ecs/system/CombatSystem.h

@@ -0,0 +1,53 @@
+#pragma once
+
+#include <optional>
+#include <vector>
+
+#include <QVector2D>
+
+#include "Building.h"
+#include "FactionComponent.h"
+#include "FireEvent.h"
+#include "GameConfig.h"
+#include "PositionComponent.h"
+#include "Tick.h"
+#include "WeaponComponent.h"
+
+#include "entt/entity/entity.hpp"
+
+class BuildingSystem;
+class EntityAdmin;
+
+class CombatSystem
+{
+public:
+    explicit CombatSystem(const GameConfig& config);
+
+    void tick(Tick currentTick,
+              EntityAdmin& admin,
+              BuildingSystem& buildings,
+              std::vector<FireEvent>& outFireEvents);
+
+    void applyPendingDamage(Tick currentTick, EntityAdmin& admin);
+
+private:
+    struct PendingDamage
+    {
+        entt::entity target;
+        float        amount;
+        Tick         appliesAt;
+    };
+
+    std::vector<PendingDamage> m_pendingDamage;
+
+    void resolveWeapon(
+        entt::entity shipEntity,
+        WeaponComponent& weapon,
+        const PositionComponent& ownPos,
+        const FactionComponent& ownFaction,
+        Tick currentTick,
+        EntityAdmin& admin,
+        std::vector<FireEvent>& out);
+
+    const GameConfig& m_config;
+};