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

include/faset/assets/asset_data.hpp

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+#pragma once
+#include <array>
+#include <cstddef>
+#include <cstdint>
+#include <filesystem>
+#include <nlohmann/json.hpp>
+#include <string>
+#include <vector>
+
+namespace faset::assets {
+using Json = nlohmann::json;
+struct Vertex {
+    std::array<float, 3> position{};
+    std::array<float, 3> normal{0, 0, 1};
+    std::array<float, 2> uv{};
+};
+struct Primitive {
+    std::vector<Vertex> vertices;
+    std::vector<std::uint32_t> indices;
+    int material = -1;
+};
+struct Mesh {
+    std::string id, name;
+    std::vector<Primitive> primitives;
+};
+struct Node {
+    std::string id, name, parent_id;
+    int mesh = -1;
+    // glTF right-handed, Y-up, metres; column-major matrix.
+    std::array<float, 16> local_transform{1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1};
+    bool stable_source_id = false;
+};
+struct Material {
+    std::string id, name;
+    std::array<float, 4> base_color{1, 1, 1, 1};
+    std::array<float, 3> emissive{};
+    float metallic = 1, roughness = 1, alpha_cutoff = 0.5f;
+    std::string alpha_mode = "OPAQUE";
+    bool double_sided = false, unlit = false;
+    int base_color_texture = -1, metallic_roughness_texture = -1;
+    int normal_texture = -1, occlusion_texture = -1, emissive_texture = -1;
+};
+struct Texture {
+    std::string id, name, mime_type;
+    // Encoded image bytes, owned by this value. Renderer selects an image decoder.
+    std::vector<std::byte> bytes;
+    int wrap_s = 10497, wrap_t = 10497, min_filter = 0, mag_filter = 0;
+};
+struct CookedAsset {
+    std::string asset_id, generation;
+    std::vector<Mesh> meshes;
+    std::vector<Node> nodes;
+    std::vector<Material> materials;
+    std::vector<Texture> textures;
+};
+
+// Read-only cooked storage. No source parser, import jobs or publication operations.
+class AssetStore {
+  public:
+    explicit AssetStore(std::filesystem::path cache_root);
+    Json current_manifest(const std::string& asset_id) const;
+    CookedAsset load_asset(const std::string& asset_id) const;
+    std::filesystem::path generation_directory(const std::string& asset_id) const;
+    const std::filesystem::path& cache_root() const noexcept {
+        return cache_root_;
+    }
+
+  protected:
+    std::filesystem::path cache_root_;
+};
+} // namespace faset::assets