Remove NaK/Rust dependency, port remaining functionality to native C++

Replace NaK Rust crate and nak_ffi with native C++ implementations:
- Game detection (Steam, Heroic, Bottles), VDF parser, icon extraction
- Prefix symlinks, SLR manager, Steam path detection
- Known games database

Add FUSE VFS optimizations: zero-copy reads via fuse_reply_data,
default_permissions mount option, FUSE_CAP_ASYNC_DIO, FUSE_CAP_EXPIRE_ONLY,
lookup cache parent index, cached mode bits, increased I/O buffer sizes.

Update build system, prefix setup, and various fixes.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

2 files changed, 18 insertions, 10 deletions

diff --git a/libs/uibase/src/CMakeLists.txt b/libs/uibase/src/CMakeLists.txt
index 3015be3..5660289 100644
--- a/libs/uibase/src/CMakeLists.txt
+++ b/libs/uibase/src/CMakeLists.txt
@@ -187,8 +187,20 @@ target_link_libraries(uibase
 	PUBLIC Qt6::Widgets Qt6::Network Qt6::QuickWidgets
 	PRIVATE spdlog::spdlog_header_only Qt6::Qml Qt6::Quick)
 
-if(NOT WIN32 AND TARGET mo2::nak_ffi)
-	target_link_libraries(uibase PRIVATE mo2::nak_ffi)
+if(NOT WIN32)
+	# Native C++ ports of game detection, Steam/Proton detection, SLR management,
+	# icon extraction, and prefix symlinks (formerly in Rust nak_ffi).
+	# Use BUILD_INTERFACE to avoid "prefixed in the source directory" CMake error.
+	target_include_directories(uibase
+		PUBLIC $<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}/src/src>)
+	target_sources(uibase PRIVATE
+		${CMAKE_SOURCE_DIR}/src/src/gamedetection.cpp
+		${CMAKE_SOURCE_DIR}/src/src/steamdetection.cpp
+		${CMAKE_SOURCE_DIR}/src/src/vdfparser.cpp
+		${CMAKE_SOURCE_DIR}/src/src/iconextractor.cpp
+		${CMAKE_SOURCE_DIR}/src/src/prefixsymlinks.cpp
+		${CMAKE_SOURCE_DIR}/src/src/slrmanager.cpp
+	)
 endif()
 
 # installation
diff --git a/libs/uibase/src/utility.cpp b/libs/uibase/src/utility.cpp
index e6811af..94cbc77 100644
--- a/libs/uibase/src/utility.cpp
+++ b/libs/uibase/src/utility.cpp
@@ -22,7 +22,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 #include <uibase/log.h>
 #include <uibase/report.h>
 #ifndef _WIN32
-#include <nak_ffi.h>
+#include "iconextractor.h"
 #endif
 #include <QApplication>
 #include <QBuffer>
@@ -946,15 +946,12 @@ QIcon iconForExecutable(const QString& filePath)
   cache.insert(cacheKey, icon);
   return icon;
 #else
-  // Extract icon from PE executable via NaK (pelite-based, no external tools).
+  // Extract icon from PE executable (native C++ parser, no external tools).
   QIcon icon;
 
   {
-    const QByteArray pathUtf8 = fi.absoluteFilePath().toUtf8();
-    NakIconData icoData = nak_extract_exe_icon(pathUtf8.constData());
-    if (icoData.data && icoData.len > 0) {
-      QByteArray ba(reinterpret_cast<const char*>(icoData.data),
-                    static_cast<qsizetype>(icoData.len));
+    QByteArray ba = extractExeIcon(fi.absoluteFilePath());
+    if (!ba.isEmpty()) {
       QBuffer buf(&ba);
       buf.open(QIODevice::ReadOnly);
       QImageReader reader(&buf, "ico");
@@ -978,7 +975,6 @@ QIcon iconForExecutable(const QString& filePath)
           }
         }
       }
-      nak_icon_data_free(icoData);
     }
   }