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, 3 deletions

diff --git a/libs/nak/src/logging.rs b/libs/nak/src/logging.rs
index 8c0f91a..e506bf8 100644
--- a/libs/nak/src/logging.rs
+++ b/libs/nak/src/logging.rs
@@ -1,7 +1,7 @@
 //! Logging for Fluorine Manager.
 //!
 //! All log messages are:
-//! 1. Written to `~/.var/app/com.fluorine.manager/logs/nak.log` (always)
+//! 1. Written to `~/.local/share/fluorine/logs/nak.log` (always)
 //! 2. Forwarded to an optional callback set via `set_log_callback()` (for MOBase::log)
 
 use std::fs;
@@ -25,8 +25,7 @@ pub fn set_log_callback(cb: impl Fn(&str, &str) + Send + Sync + 'static) {
 
 /// Get the log directory path.
 fn log_dir() -> PathBuf {
-    let home = std::env::var("HOME").unwrap_or_else(|_| "/tmp".to_string());
-    PathBuf::from(home).join(".var/app/com.fluorine.manager/logs")
+    crate::paths::data_dir().join("logs")
 }
 
 /// Get the log file path.