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, 2 insertions, 4 deletions

diff --git a/libs/nak/src/dxvk.rs b/libs/nak/src/dxvk.rs
index 97e4222..b335773 100644
--- a/libs/nak/src/dxvk.rs
+++ b/libs/nak/src/dxvk.rs
@@ -1,7 +1,7 @@
 //! DXVK configuration management for Fluorine Manager.
 //!
 //! Downloads dxvk.conf from upstream, appends Fluorine-specific settings,
-//! and stores at `~/.var/app/com.fluorine.manager/config/dxvk.conf`.
+//! and stores at `~/.local/share/fluorine/config/dxvk.conf`.
 
 use std::error::Error;
 use std::fs;
@@ -20,9 +20,7 @@ dxvk.enableGraphicsPipelineLibrary = False
 
 /// Get the path where the DXVK config will be stored.
 pub fn get_dxvk_conf_path() -> PathBuf {
-    let home = std::env::var("HOME").unwrap_or_else(|_| "/tmp".to_string());
-    PathBuf::from(home)
-        .join(".var/app/com.fluorine.manager/config/dxvk.conf")
+    crate::paths::data_dir().join("config/dxvk.conf")
 }
 
 /// Ensure the dxvk.conf file exists, downloading if necessary.