port 2A step 4: platform skeleton + rest of the 2V3 header closure

- Mirror the remaining non-Python 2V3 closure headers (98 more, 173 total): EffectLib,
  EterGrnLib, SpeedTreeLib, SphereLib, PRTerrainLib, EterImageLib, EterBase/Poly, cipher/tea,
  EterLib Grp*/IME/Input/MSWindow/StateManager, GameLib actor/map/race headers, EterPack.
- SDK shims: granny.h, SpeedTreeRT.h, imm.h, Dimm.h (the SDK MIDL header, not mirrored),
  dinput/d3dx8 additions; D3D8 render-state enums, FVF macros and the COM resource hierarchy;
  more Win32 GDI/handle types with layout static_asserts.
- PORT edits for MSVC-permissive code (typename, friend visibility, <algorithm>, pointer→uintptr_t)
  and PRTerrainLib/StdAfx.h dropping the ScriptLib/Python include.
- port_logic links the vendored cryptopp/minilzo.
- extension/src/platform: port_platform target with 103 generated stub files (1917 function
  stubs, 146 static members) from the new platform_stub.py (clang -ast-dump-filter);
  MT_PLATFORM_STUB() marks every unimplemented body. libmtgodot links port_platform and
  port_gate.sh builds it.

Gate: macOS, Android, iOS, Windows (mingw) PASS; Linux BLOCKED (no toolchain).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

extension/src/platform/EterLib/Mutex.cpp

@@ -0,0 +1,32 @@
+// Platform skeleton for EterLib/Mutex.h (40250 EterLib/Mutex.cpp), generated by platform_stub.py.
+// Every MT_PLATFORM_STUB() body is unimplemented: replace it with the platform implementation.
+#include "EterLib/StdAfx.h"
+#include "EterLib/Mutex.h"
+
+#include "../PlatformStub.h"
+
+Mutex::Mutex()
+{
+	MT_PLATFORM_STUB();
+}
+
+Mutex::~Mutex()
+{
+	MT_PLATFORM_STUB();
+}
+
+auto Mutex::Lock() -> void
+{
+	MT_PLATFORM_STUB();
+}
+
+auto Mutex::Unlock() -> void
+{
+	MT_PLATFORM_STUB();
+}
+
+auto Mutex::Trylock() -> bool
+{
+	MT_PLATFORM_STUB();
+	return mt_platform_stub_return<bool>();
+}