port(EterLib): Mutex/Thread/FileLoaderThread/GrpVertexBufferDynamic verbatim over Win32Crt kernel-object shims

Adds CreateSemaphore/ReleaseSemaphore/WaitForSingleObject/CloseHandle/
SetThreadPriority/_beginthreadex to Win32Crt; port.file_loader_thread covers
the shims, CThread and both the un-Created (40250 live) and Created loader.

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

src/platform/EterLib/Thread.cpp

@@ -1,29 +1,34 @@
-// Platform skeleton for EterLib/Thread.h (40250 EterLib/Thread.cpp), generated by platform_stub.py.
-// Every MT_PLATFORM_STUB() body is unimplemented: replace it with the platform implementation.
+// 40250 EterLib/Thread.cpp, verbatim. The kernel32 calls resolve to the Win32Crt thread/semaphore/critical-section shims.
 #include "EterLib/StdAfx.h"
 #include "EterLib/Thread.h"
 
-#include "../PlatformStub.h"
-
-CThread::CThread()
+CThread::CThread() : m_pArg(NULL), m_hThread(NULL), m_uThreadID(0)
 {
-	MT_PLATFORM_STUB();
 }
 
-auto CThread::Create(void *) -> int
+int CThread::Create(void * arg)
 {
-	MT_PLATFORM_STUB();
-	return mt_platform_stub_return<int>();
+	Arg(arg);
+	m_hThread = (HANDLE) _beginthreadex(NULL, 0, EntryPoint, this, 0, &m_uThreadID);
+
+	if (!m_hThread)
+		return false;
+
+	SetThreadPriority(m_hThread, THREAD_PRIORITY_NORMAL);
+	return true;
 }
 
-auto CThread::EntryPoint(void *) -> UINT
+UINT CThread::Run(void * arg)
 {
-	MT_PLATFORM_STUB();
-	return mt_platform_stub_return<UINT>();
+	if (!Setup())
+		return 0;
+
+	return (Execute(arg));
 }
 
-auto CThread::Run(void *) -> UINT
+/* Static */
+UINT CALLBACK CThread::EntryPoint(void * pThis)
 {
-	MT_PLATFORM_STUB();
-	return mt_platform_stub_return<UINT>();
+	CThread * pThread = (CThread *) pThis;
+	return pThread->Run(pThread->Arg());
 }