Add Python init diagnostics, AppImage build system, misc Linux fixes

- python: switch Py_InitializeEx → Py_InitializeFromConfig for explicit
  error reporting; add dladdr + fprintf diagnostics to trace which DSO
  Python symbols resolve to and whether Py_IsInitialized succeeds
- python: log RTLD_NOLOAD vs fresh-load outcome when promoting libpython
  to RTLD_GLOBAL
- build: add Docker-based AppImage build script (build.sh), update
  Dockerfile and build-inner.sh for AppImage-only workflow
- build: remove Flatpak support entirely; move AppImage metadata
  (desktop/metainfo/icon) from flatpak/ to data/
- Add Monster Hunter Wilds basic_games plugin
- .gitignore: exclude squashfs-root, build-source, flatpak-repo,
  __pycache__, fomod-plus-settings.ini
- Various Linux port fixes across wineprefix, processrunner, proton
  launcher, FUSE connector, instance manager, download manager,
  sanitychecks, and NaK Rust paths/runtime_wrap

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

2 files changed, 3 insertions, 39 deletions

diff --git a/libs/nak/src/paths.rs b/libs/nak/src/paths.rs
index e86c284..f6dde6c 100644
--- a/libs/nak/src/paths.rs
+++ b/libs/nak/src/paths.rs
@@ -1,11 +1,11 @@
 //! Shared data directory for Fluorine Manager.
 //!
-//! All data lives under `~/.var/app/com.fluorine.manager/`.
+//! All data lives under `~/.local/share/fluorine/`.
 
 use std::path::PathBuf;
 
-/// Returns the Fluorine data directory (`~/.var/app/com.fluorine.manager`).
+/// Returns the Fluorine data directory (`~/.local/share/fluorine`).
 pub fn data_dir() -> PathBuf {
     let home = std::env::var("HOME").unwrap_or_else(|_| "/tmp".to_string());
-    PathBuf::from(home).join(".var/app/com.fluorine.manager")
+    PathBuf::from(home).join(".local/share/fluorine")
 }
diff --git a/libs/nak/src/runtime_wrap.rs b/libs/nak/src/runtime_wrap.rs
index d33bd59..9b5ff89 100644
--- a/libs/nak/src/runtime_wrap.rs
+++ b/libs/nak/src/runtime_wrap.rs
@@ -34,23 +34,6 @@ fn find_in_path(binary: &str) -> Option<PathBuf> {
 }
 
 pub fn resolve_umu_run() -> Option<PathBuf> {
-    if is_flatpak() {
-        // In Flatpak, umu-run must run on the host via flatpak-spawn --host.
-        let host_copy = env::var("XDG_DATA_HOME")
-            .ok()
-            .map(PathBuf::from)
-            .unwrap_or_else(|| {
-                let home = env::var("HOME").unwrap_or_else(|_| "/tmp".to_string());
-                PathBuf::from(home).join(".local/share")
-            })
-            .join("fluorine/umu-run");
-        if host_copy.exists() {
-            return Some(host_copy);
-        }
-        // Fall back to bare name for host PATH resolution.
-        return Some(PathBuf::from("umu-run"));
-    }
-
     let bundled = env::var("NAK_BUNDLED_UMU_RUN")
         .ok()
         .map(PathBuf::from)
@@ -64,14 +47,8 @@ pub fn resolve_umu_run() -> Option<PathBuf> {
     }
 }
 
-pub fn is_flatpak() -> bool {
-    Path::new("/.flatpak-info").exists()
-}
-
 /// Build a command to run `exe` with the given environment variables.
 ///
-/// In Flatpak mode, `flatpak-spawn --host` is used and env vars are passed as
-/// `--env=KEY=VALUE` flags (the host process does NOT inherit the sandbox env).
 /// In steam-run mode, the command is wrapped with `steam-run`.
 /// Otherwise the command runs directly.
 pub fn build_command<S: AsRef<OsStr>>(
@@ -86,19 +63,6 @@ pub fn build_command<S: AsRef<OsStr>>(
         }
         return cmd;
     }
-    if is_flatpak() {
-        let mut cmd = Command::new("flatpak-spawn");
-        cmd.arg("--host");
-        for (key, value) in envs {
-            cmd.arg(format!(
-                "--env={}={}",
-                key,
-                value.as_ref().to_string_lossy()
-            ));
-        }
-        cmd.arg(exe.as_ref());
-        return cmd;
-    }
     let mut cmd = Command::new(exe);
     for (key, value) in envs {
         cmd.env(key, value.as_ref());