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

apps/schema_exporter_main.cpp

@@ -0,0 +1,35 @@
+#include "Gameplay.hpp"
+#include <faset/core/io.hpp>
+#include <iostream>
+#include <stdexcept>
+
+int main(int argc, char** argv) {
+    try {
+        std::filesystem::path output;
+        for (int i = 1; i < argc; ++i) {
+            const std::string argument = argv[i];
+            if (argument == "--help") {
+                std::cout << "faset_schema_exporter [--output PATH]\nExports declarative gameplay "
+                             "schemas without creating a world.\n";
+                return 0;
+            }
+            if (argument == "--output" && i + 1 < argc && output.empty())
+                output = argv[++i];
+            else
+                throw std::invalid_argument("Unknown, repeated or incomplete argument: " +
+                                            argument);
+        }
+        const auto types = faset::gameplay::schema();
+        if (!types.is_array())
+            throw std::runtime_error("Gameplay schema() must return a type array");
+        const nlohmann::json manifest{{"format", "faset.schema"}, {"version", 1}, {"types", types}};
+        if (output.empty())
+            std::cout << manifest.dump(2) << '\n';
+        else
+            faset::atomic_write_json(output, manifest);
+        return 0;
+    } catch (const std::exception& error) {
+        std::cerr << "Schema export failed: " << error.what() << '\n';
+        return 1;
+    }
+}