Implement unit action queueing and busy state validation

unit.cpp

@@ -35,12 +35,72 @@ float Unit::getTerrainHeight(float worldX, float worldY, Matrix2D<TerrainPoint>
     return (h / 255.0f) * 3.5f + 1.0f;
 }
 
+bool Unit::queueAction(const UnitAction &action)
+{
+    if ((int)actionQueue.size() >= maxQueueSize) {
+        return false;
+    }
+    actionQueue.push_back(action);
+    return true;
+}
+
+void Unit::clearActionQueue()
+{
+    actionQueue.clear();
+}
+
+bool Unit::hasQueuedActionType(UnitActionType type) const
+{
+    for (const auto &act : actionQueue) {
+        if (act.type == type) return true;
+    }
+    return false;
+}
+
+void Unit::removeQueuedActionsOfType(UnitActionType type)
+{
+    for (auto it = actionQueue.begin(); it != actionQueue.end(); ) {
+        if (it->type == type) {
+            it = actionQueue.erase(it);
+        } else {
+            ++it;
+        }
+    }
+}
+
+UnitAction Unit::popNextQueuedAction()
+{
+    if (actionQueue.empty()) return UnitAction();
+    UnitAction act = actionQueue.front();
+    actionQueue.pop_front();
+    return act;
+}
+
+const UnitAction* Unit::peekNextQueuedAction() const
+{
+    if (actionQueue.empty()) return nullptr;
+    return &actionQueue.front();
+}
+
+QString Unit::getQueuedActionSummary() const
+{
+    if (actionQueue.empty()) return "";
+    switch (actionQueue.front().type) {
+    case UnitActionType::Move:
+        return "Move";
+    case UnitActionType::BuildImprovement:
+        return "Build Farm";
+    case UnitActionType::BuildCity:
+        return "Found City";
+    case UnitActionType::Attack:
+        return "Attack";
+    default:
+        return "Action";
+    }
+}
+
 void Unit::setPath(const std::vector<std::pair<int, int>> &newPath)
 {
-    if (state == UnitState::Building) {
-        cancelBuilding();
-    }
-
     path = newPath;
     pathIndex = 0;
     moveProgress = 0.0f;
@@ -60,6 +120,7 @@ void Unit::stopMovement()
     pathIndex = 0;
     moveProgress = 0.0f;
     state = UnitState::Idle;
+    clearActionQueue();
 }
 
 void Unit::startBuilding(const QString &impId, float duration)