Checkpoint 2: integrate native Editor, MCP, gameplay builds and standalone export

examples/tutorials/following/Gameplay.cpp

@@ -0,0 +1,43 @@
+#include "Gameplay.hpp"
+
+namespace faset::gameplay {
+void registerGameplay(runtime::Runtime& world) {
+    runtime::Behavior motion;
+    motion.fixedUpdate = [](runtime::Runtime& game, runtime::EntityHandle self, double delta) {
+        auto pose = game.transform(self);
+        pose.position[0] += game.fields(self, "tutorial.fixed_move").value("speed", 2.0f) *
+                            static_cast<float>(delta);
+        game.setTransform(self, pose);
+    };
+    world.registerBehavior("tutorial.fixed_move", std::move(motion));
+
+    runtime::Behavior follow;
+    follow.lateUpdate = [](runtime::Runtime& game, runtime::EntityHandle self, double) {
+        const auto settings = game.fields(self, "tutorial.follow");
+        const auto target = game.find(settings.value("target", std::string{}));
+        if (!game.valid(target))
+            return;                                        // Target may be absent or destroyed.
+        const auto targetPose = game.presentation(target); // Already interpolated.
+        const auto offset = settings.at("offset").get<runtime::Vec3>();
+        auto cameraPose = game.presentation(self);
+        for (int axis = 0; axis < 3; ++axis)
+            cameraPose.position[axis] = targetPose.position[axis] + offset[axis];
+        game.setPresentation(self, cameraPose); // Does not write the simulation pose.
+    };
+    world.registerBehavior("tutorial.follow", std::move(follow));
+}
+
+nlohmann::json schema() {
+    return nlohmann::json::array(
+        {{{"id", "tutorial.fixed_move"},
+          {"version", 1},
+          {"name", "Fixed movement"},
+          {"fields", {{"speed", {{"id", "speed"}, {"type", "number"}, {"default", 2.0}}}}}},
+         {{"id", "tutorial.follow"},
+          {"version", 1},
+          {"name", "Follow presentation"},
+          {"fields",
+           {{"target", {{"id", "target"}, {"type", "entity_ref"}, {"default", "actor"}}},
+            {"offset", {{"id", "offset"}, {"type", "vec3"}, {"default", {0, 0, 10}}}}}}}});
+}
+} // namespace faset::gameplay