Remove umu-run, keep game as child process for Steam tracking

- Remove umu-run entirely (crashed due to pressure-vessel/FUSE
  incompatibility) — use raw `proton run` instead
- Replace startDetached() with QProcess::start() so the game stays in
  Fluorine's process tree. This lets Steam track the game lifetime and
  makes the "close game" button work when Fluorine is added as a
  non-Steam game.
- Add writeIniValueDirect/readIniValueDirect for safe Bethesda INI
  handling without QSettings corruption
- Fix prefix_setup.rs to skip umu-run bootstrapping
- Clean up settings UI, build scripts, and docs for umu-run removal

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

2 files changed, 3 insertions, 56 deletions

diff --git a/libs/nak/src/installers/prefix_setup.rs b/libs/nak/src/installers/prefix_setup.rs
index 4f27606..468aaa2 100644
--- a/libs/nak/src/installers/prefix_setup.rs
+++ b/libs/nak/src/installers/prefix_setup.rs
@@ -297,23 +297,9 @@ fn initialize_prefix_with_proton(
         ("WINEDLLOVERRIDES", "msdia80.dll=n;conhost.exe=d;cmd.exe=d".to_string()),
     ];
 
-    let (exe, args): (std::path::PathBuf, Vec<&str>) = if runtime_wrap::use_umu_for_prefix() {
-        if let Some(umu_run) = runtime_wrap::resolve_umu_run() {
-            log_install(&format!("Initializing prefix with umu-run: {:?}", umu_run));
-            envs.push(("PROTONPATH", proton.path.display().to_string()));
-            envs.push(("WINEPREFIX", prefix_root.display().to_string()));
-            envs.push(("GAMEID", app_id.to_string()));
-            (umu_run, vec!["wineboot", "-u"])
-        } else {
-            log_warning(
-                "UMU prefix mode enabled but no umu-run was found; falling back to proton wrapper",
-            );
-            (proton_script.clone(), vec!["run", "wineboot", "-u"])
-        }
-    } else {
-        log_install(&format!("Initializing prefix with proton wrapper: {:?}", proton_script));
-        (proton_script.clone(), vec!["run", "wineboot", "-u"])
-    };
+    log_install(&format!("Initializing prefix with proton wrapper: {:?}", proton_script));
+    let (exe, args): (std::path::PathBuf, Vec<&str>) =
+        (proton_script.clone(), vec!["run", "wineboot", "-u"]);
 
     let mut cmd = runtime_wrap::build_command(&exe, &envs);
     cmd.args(&args);
diff --git a/libs/nak/src/runtime_wrap.rs b/libs/nak/src/runtime_wrap.rs
index 9b5ff89..69f693e 100644
--- a/libs/nak/src/runtime_wrap.rs
+++ b/libs/nak/src/runtime_wrap.rs
@@ -1,6 +1,5 @@
 use std::env;
 use std::ffi::OsStr;
-use std::path::{Path, PathBuf};
 use std::process::Command;
 
 fn env_flag(name: &str) -> bool {
@@ -18,35 +17,6 @@ pub fn use_steam_run() -> bool {
     env_flag("NAK_USE_STEAM_RUN")
 }
 
-pub fn use_umu_for_prefix() -> bool {
-    env_flag("NAK_USE_UMU_FOR_PREFIX")
-}
-
-pub fn prefer_system_umu() -> bool {
-    env_flag("NAK_PREFER_SYSTEM_UMU")
-}
-
-fn find_in_path(binary: &str) -> Option<PathBuf> {
-    let path = env::var_os("PATH")?;
-    env::split_paths(&path)
-        .map(|entry| entry.join(binary))
-        .find(|candidate| candidate.exists())
-}
-
-pub fn resolve_umu_run() -> Option<PathBuf> {
-    let bundled = env::var("NAK_BUNDLED_UMU_RUN")
-        .ok()
-        .map(PathBuf::from)
-        .filter(|p| p.exists());
-    let system = find_in_path("umu-run");
-
-    if prefer_system_umu() {
-        system.or(bundled)
-    } else {
-        bundled.or(system)
-    }
-}
-
 /// Build a command to run `exe` with the given environment variables.
 ///
 /// In steam-run mode, the command is wrapped with `steam-run`.
@@ -74,12 +44,3 @@ pub fn build_command<S: AsRef<OsStr>>(
 pub fn command_for(exe: impl AsRef<OsStr>) -> Command {
     build_command::<&str>(exe, &[])
 }
-
-pub fn bundled_umu_path_from_appdir(appdir: &Path) -> Option<PathBuf> {
-    let path = appdir.join("umu-run");
-    if path.exists() {
-        Some(path)
-    } else {
-        None
-    }
-}