Merge branch 'alpha'

The xcompress.h header and XMem compression functions require Windows.h
and the Xbox SDK, which are not available on macOS. Wrap all XMem
functions with #ifdef Q_OS_WIN and provide stub implementations that
return empty data on non-Windows platforms.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

libs/compression/compression.cpp

@@ -1,6 +1,9 @@
 #include "compression.h"
 #include "minilzo.h"
+
+#ifdef Q_OS_WIN
 #include "xcompress.h"
+#endif
 
 // libmspack for LZX decompression
 extern "C" {
@@ -229,6 +232,7 @@ QString Compression::quickBmsPath()
     return s_quickBmsPath;
 }
 
+#ifdef Q_OS_WIN
 QByteArray Compression::CompressXMem(const QByteArray &data)
 {
     XMEMCODEC_PARAMETERS_LZX lzxParams = {};
@@ -253,7 +257,15 @@ QByteArray Compression::CompressXMem(const QByteArray &data)
     output.resize(static_cast<int>(actualSize));
     return output;
 }
+#else
+QByteArray Compression::CompressXMem(const QByteArray &)
+{
+    qWarning() << "XMem compression not available on this platform";
+    return {};
+}
+#endif
 
+#ifdef Q_OS_WIN
 QByteArray Compression::DecompressXMem(const QByteArray &data,
                                        int flags, int windowSize, int partSize)
 {
@@ -479,6 +491,32 @@ QByteArray Compression::DecompressXMemRaw(const QByteArray &data, int flags, int
     XMemDestroyDecompressionContext(ctx);
     return output;
 }
+#else
+// Non-Windows stub implementations
+QByteArray Compression::DecompressXMem(const QByteArray &, int, int, int)
+{
+    qWarning() << "XMem decompression not available on this platform";
+    return {};
+}
+
+QByteArray Compression::DecompressXMemNative(const QByteArray &)
+{
+    qWarning() << "XMem native decompression not available on this platform";
+    return {};
+}
+
+QByteArray Compression::DecompressXMemTDecode(const QByteArray &, int, int, int)
+{
+    qWarning() << "XMem TDecode decompression not available on this platform";
+    return {};
+}
+
+QByteArray Compression::DecompressXMemRaw(const QByteArray &, int, int, int)
+{
+    qWarning() << "XMem raw decompression not available on this platform";
+    return {};
+}
+#endif
 
 // ============================================================================
 // lzxdhelper-style LZX decompression (UE Viewer/Gildor approach)