Migrate data paths to ~/.local/share/fluorine/, add native build, fix %command% and system Proton scanning

- All data paths migrated from ~/.var/app/com.fluorine.manager/ to
  ~/.local/share/fluorine/ so native and Flatpak builds share the same
  instances, plugins, and configs
- New fluorinepaths.h/.cpp with fluorineDataDir() helper and one-time
  migration from old path (writes MOVED.txt breadcrumb)
- New libs/nak/src/paths.rs as Rust equivalent (data_dir())
- Strip %command% tokens from launch wrapper in protonlauncher.cpp
- Always scan /usr/share/steam/compatibilitytools.d/ for system Proton
  packages (Arch installs Proton there); add Flatpak filesystem permission
- Native build (build-native.sh) installs to ~/.local/share/fluorine/
  with desktop entry and ~/.local/bin symlink instead of portable zip
- build-flatpak.sh wrapper for Flatpak builds
- Fix container locale (LANG=C.UTF-8) for AutoUic warnings
- Fix prefixExists() to handle both compatdata and pfx directory layouts
- Fix globalInstancesRootPath() to use fluorineDataDir() on Linux
- Fix umu-run Flatpak lookup to use fluorineDataDir()
- Update README with build instructions and Arch dependency list

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 16 insertions, 2 deletions

diff --git a/libs/uibase/src/utility.cpp b/libs/uibase/src/utility.cpp
index 0ad64ad..e6f53b8 100644
--- a/libs/uibase/src/utility.cpp
+++ b/libs/uibase/src/utility.cpp
@@ -64,7 +64,17 @@ bool removeDir(const QString& dirName)
                dir.entryInfoList(QDir::NoDotAndDotDot | QDir::System | QDir::Hidden |
                                      QDir::AllDirs | QDir::Files,
                                  QDir::DirsFirst)) {
-      if (info.isDir()) {
+      // Never recurse into symlinked directories: in Flatpak they can point to
+      // read-only runtime locations (e.g. /app), and we only want to remove the link.
+      if (info.isSymLink()) {
+        QFile file(info.absoluteFilePath());
+        if (!file.remove()) {
+          reportError(QObject::tr("removal of \"%1\" failed: %2")
+                          .arg(info.absoluteFilePath())
+                          .arg(file.errorString()));
+          return false;
+        }
+      } else if (info.isDir()) {
         if (!removeDir(info.absoluteFilePath())) {
           return false;
         }
@@ -209,7 +219,11 @@ static bool shellOpDelete(const QStringList& fileNames, bool recycle)
   // On Linux, "recycle" moves to trash using Qt; otherwise just delete
   for (const auto& fileName : fileNames) {
     QFileInfo fi(fileName);
-    if (fi.isDir()) {
+    if (fi.isSymLink()) {
+      if (!QFile::remove(fileName)) {
+        return false;
+      }
+    } else if (fi.isDir()) {
       if (!removeDir(fileName)) {
         return false;
       }