Windows: Fix a batch of MSVC warnings from CI

Signed/unsigned comparisons, bool/int mixes and narrowing in our own code,
plus duplicate NOMINMAX defines. The UWP Common/Core/UI projects now define
_CRT_NO_POSIX_ERROR_CODES like the desktop ones, so SocketCompat.h no longer
redefines the errno macros there. ImMemView's byte search no longer strdup()s
the query (it leaked on the error path).

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

Core/Util/GameManager.cpp

@@ -670,7 +670,7 @@ bool GameManager::ExtractFile(struct zip *z, int file_index, const Path &outFile
 			size_t readSize = std::min(blockSize, size - pos);
 			// Stop before the total would exceed the limit (zip bomb), even
 			// if the declared sizes in the archive were inaccurate.
-			if (*bytesCopied > maxTotalSize || readSize > maxTotalSize - *bytesCopied) {
+			if (*bytesCopied > maxTotalSize || (int64_t)readSize > maxTotalSize - *bytesCopied) {
 				ERROR_LOG(Log::HLE, "Bailing: zip contents too large, limit %d", (int)maxTotalSize);
 				delete[] buffer;
 				fclose(f);