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>

extension/src/platform/pending/UserInterface/PythonBackground.cpp

@@ -94,3 +94,69 @@ auto CPythonBackground::GetPickingPointWithRayOnlyTerrain(const CRay &, D3DXVECT
 	MT_PLATFORM_STUB();
 	return mt_platform_stub_return<bool>();
 }
+
+auto CPythonBackground::GetFarClip() -> float
+{
+	MT_PLATFORM_STUB();
+	return mt_platform_stub_return<float>();
+}
+
+auto CPythonBackground::Render() -> void
+{
+	MT_PLATFORM_STUB();
+}
+
+auto CPythonBackground::RenderAfterLensFlare() -> void
+{
+	MT_PLATFORM_STUB();
+}
+
+auto CPythonBackground::RenderBeforeLensFlare() -> void
+{
+	MT_PLATFORM_STUB();
+}
+
+auto CPythonBackground::RenderCharacterShadowToTexture() -> void
+{
+	MT_PLATFORM_STUB();
+}
+
+auto CPythonBackground::RenderCloud() -> void
+{
+	MT_PLATFORM_STUB();
+}
+
+auto CPythonBackground::RenderEffect() -> void
+{
+	MT_PLATFORM_STUB();
+}
+
+auto CPythonBackground::RenderPCBlocker() -> void
+{
+	MT_PLATFORM_STUB();
+}
+
+auto CPythonBackground::RenderSky() -> void
+{
+	MT_PLATFORM_STUB();
+}
+
+auto CPythonBackground::RenderSnow() -> void
+{
+	MT_PLATFORM_STUB();
+}
+
+auto CPythonBackground::RenderWater() -> void
+{
+	MT_PLATFORM_STUB();
+}
+
+auto CPythonBackground::SetBackgroundDirLight() -> void
+{
+	MT_PLATFORM_STUB();
+}
+
+auto CPythonBackground::SetCharacterDirLight() -> void
+{
+	MT_PLATFORM_STUB();
+}

extension/src/platform/pending/UserInterface/PythonItem.cpp

@@ -55,3 +55,13 @@ auto CPythonItem::SetOwnership(DWORD, const char *) -> void
 {
 	MT_PLATFORM_STUB();
 }
+
+auto CPythonItem::Render() -> void
+{
+	MT_PLATFORM_STUB();
+}
+
+auto CPythonItem::Update(const POINT &) -> void
+{
+	MT_PLATFORM_STUB();
+}