port 2V2-d.2: Granny runtime on libgr2, main character model animates

Implement the Granny SDK 2.11 API the client uses on top of libgr2
(platform/EterGrnLib/GrannyRuntime.cpp, shim granny.h declared from the
SDK header): file sections, type-definition vertex conversion, material
textures by Usage, mesh/bone bindings, deformer, control clock/loop/ease
and weighted SRT sampling. Port EterGrnLib (LODController, Material, Mesh,
Model, ModelInstance*, Motion, Thing, ThingInstance, Util) plus EterLib
GrpObjectInstance/GrpCollisionObject/CollisionData verbatim and drop their
platform skeletons and pending stand-ins; register the gr2 resource
factory; vertex/index buffers are CPU-side until the 2V2-e render adapter.

app.UpdateGame/RenderGame now run 40250's bodies, reaching the
CPythonApplication members through their singletons (the platform has no
app object); CPythonGraphic joins GameSingletons in member order, and
GetMousePosition reads the host cursor.

port.login_flow asserts the main instance's PART_MAIN model has meshes,
its diffuse image loaded and the WAIT motion moves the bones between
frames; offline and live pass, port_gate macos PASS.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

libgr2/src/internal.h

@@ -125,6 +125,15 @@ struct File::Impl {
 
     // granny_transform (68B) → 行主序 4x4（BuildCompositeTransform4x4 语义）
     void transform_to_composite(Ref tf, Mat4& out, uint32_t& flags) const;
+    void read_transform(Ref tf, Transform& out) const;             // 68B → SRT 分量
+
+    // granny_material 图：按对象 Ref 去重，缺的追加到 mats_out（子材质 / 只经 mesh 可达的材质）。
+    // 返回 FileInfo::materials 索引；无效 / 递归太深 = -1。
+    int32_t  intern_material(Ref mat_obj, Ref mat_type, int depth = 0);
+    std::vector<Material>* mats_out = nullptr;
+    std::vector<Ref>       mat_refs;      // 与 *mats_out 平行
+    // ExtendedData（VariantRef = {type ptr; object ptr}）里取名为 name 的 Int32。
+    bool     extended_i32(Ref variant_slot, const char* name, int32_t& out);
 
     std::vector<Skeleton> skels_cache;   // self-check 复用
     std::vector<Ref>      skel_refs;     // 与 skels_cache 平行：各 skeleton 对象的 Ref（model 关联用）