feat(entities): bloc collision i anchor:feet per entitats amb falsa perspectiva

source/game/entities/entity.cpp

@@ -26,3 +26,18 @@ void Entity::onPlayerContact(Player* /*player*/) {
 void Entity::notifyTileEntered(int /*col*/, int /*row*/) {
     // No-op per defecte; només `Sarcophagus` l'usa.
 }
+
+auto Entity::getCollisionRect() const -> SDL_FRect {
+    if (!collision_box_.has_value()) { return pixel_rect_; }
+    return {
+        .x = pixel_rect_.x + static_cast<float>(collision_box_->offset_x),
+        .y = pixel_rect_.y + static_cast<float>(collision_box_->offset_y),
+        .w = static_cast<float>(collision_box_->width),
+        .h = static_cast<float>(collision_box_->height),
+    };
+}
+
+auto Entity::getFeetY() const -> float {
+    const auto RECT = getCollisionRect();
+    return RECT.y + RECT.h;
+}