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, 4 insertions, 5 deletions

diff --git a/libs/nak/src/deps/tools.rs b/libs/nak/src/deps/tools.rs
index c97247c..0e3e356 100644
--- a/libs/nak/src/deps/tools.rs
+++ b/libs/nak/src/deps/tools.rs
@@ -1,7 +1,7 @@
 //! Linux tool management (winetricks, cabextract)
 //!
 //! Handles downloading and managing Linux CLI tools.
-//! Tools are stored in ~/.var/app/com.fluorine.manager/bin/ for Fluorine Manager.
+//! Tools are stored in ~/.local/share/fluorine/bin/ for Fluorine Manager.
 
 use std::error::Error;
 use std::fs;
@@ -13,14 +13,13 @@ use std::process::Command;
 use crate::logging::{log_error, log_info, log_warning};
 
 // ============================================================================
-// NaK Bin Directory (~/.var/app/com.fluorine.manager/bin/)
+// NaK Bin Directory (~/.local/share/fluorine/bin/)
 // ============================================================================
 
-/// Get the tool bin directory path (~/.var/app/com.fluorine.manager/bin/)
+/// Get the tool bin directory path (~/.local/share/fluorine/bin/)
 /// This is accessible from both native and Flatpak environments.
 pub fn get_nak_bin_path() -> PathBuf {
-    let home = std::env::var("HOME").unwrap_or_else(|_| "/tmp".to_string());
-    PathBuf::from(home).join(".var/app/com.fluorine.manager/bin")
+    crate::paths::data_dir().join("bin")
 }
 
 /// Check if a command exists (either in system PATH or tool bin)