implement waves

src/lib/sim/ShipSystem.h

@@ -47,6 +47,10 @@ public:
     // -- Movement (tick-order step 10) ---------------------------------------
     void tickMovement();
 
+    // Reduce ship HP by amount. Does not remove the ship; step 9 handles death.
+    // Returns false if ship not found.
+    bool damageShip(EntityId id, float amount);
+
 private:
     const ShipDef* findShipDef(const std::string& blueprintId) const;