fix(desktop): self-update rebuilds and relaunches cleanly on macOS

The macOS DMG / in-app update could leave Hermes unable to relaunch: the
staged updater rebuilt the desktop without managed Node on PATH ("npm not
found"), never installed the rebuilt bundle over the running app, and could
race itself on `git stash`. Child install scripts also inherited a deleted
cwd from the .app bundle replaced during self-update.

- update.rs: prepend $HERMES_HOME/node/bin + venv bin to the rebuild PATH;
  read --branch / --target-app from args; add a macOS "install" stage that
  dittos the rebuilt bundle over the target app, clears quarantine, and
  relaunches via `open` (rolling back on a failed swap); guard start_update
  with an AtomicBool so concurrent startUpdate() calls can't race git stash.
- main.cjs: pass --branch <configured> and --target-app <running bundle> to
  the staged updater, and spawn it with HERMES_HOME + managed Node/venv on
  PATH and cwd=HERMES_HOME.
- bootstrap.rs: launch the desktop via `open <App>.app` on macOS instead of
  exec'ing Contents/MacOS/Hermes, avoiding cwd/quarantine issues post-rebuild.
- powershell.rs: pin child install scripts to a stable cwd so they don't emit
  getcwd errors when the launching .app is replaced mid-install.
- failure.tsx: in update mode show "Update didn't finish" / "Retry update"
  and retry via startUpdate() instead of re-running the installer bootstrap.

apps/bootstrap-installer/src-tauri/src/bootstrap.rs

@@ -179,9 +179,11 @@ pub async fn launch_hermes_desktop(
 
     tracing::info!(?exe_path, "launching Hermes desktop");
 
-    // Detach from us — the installer is about to exit.
-    let mut cmd = tokio::process::Command::new(&exe_path);
-    cmd.current_dir(exe_path.parent().unwrap_or(&install_root));
+    // Detach from us — the installer is about to exit. On macOS launch the
+    // bundle through LaunchServices instead of exec'ing Contents/MacOS/Hermes
+    // directly; this matches user double-click/open behavior and avoids cwd /
+    // quarantine oddities after a self-update rebuild.
+    let mut cmd = desktop_launch_command(&exe_path, &install_root);
     #[cfg(target_os = "windows")]
     {
         use std::os::windows::process::CommandExt;
@@ -232,6 +234,24 @@ pub(crate) fn resolve_hermes_desktop_exe(install_root: &std::path::Path) -> Opti
     None
 }
 
+pub(crate) fn resolve_hermes_desktop_app(install_root: &std::path::Path) -> Option<PathBuf> {
+    let exe = resolve_hermes_desktop_exe(install_root)?;
+    #[cfg(target_os = "macos")]
+    {
+        // .../Hermes.app/Contents/MacOS/Hermes -> .../Hermes.app
+        let app = exe.parent()?.parent()?.parent()?.to_path_buf();
+        if app.extension().and_then(|e| e.to_str()) == Some("app") && app.is_dir() {
+            return Some(app);
+        }
+    }
+    #[cfg(not(target_os = "macos"))]
+    {
+        return Some(exe);
+    }
+    #[allow(unreachable_code)]
+    None
+}
+
 /// True when a prior install completed (bootstrap-complete marker present) AND a
 /// launchable desktop app exists on disk. Used by the installer's launcher fast
 /// path so a bare re-open just opens Hermes instead of re-running setup.
@@ -247,8 +267,7 @@ pub(crate) fn spawn_installed_desktop(install_root: &std::path::Path) -> std::io
     let exe = resolve_hermes_desktop_exe(install_root).ok_or_else(|| {
         std::io::Error::new(std::io::ErrorKind::NotFound, "no built Hermes desktop app")
     })?;
-    let mut cmd = std::process::Command::new(&exe);
-    cmd.current_dir(exe.parent().unwrap_or(install_root));
+    let mut cmd = desktop_launch_command_std(&exe, install_root);
     #[cfg(target_os = "windows")]
     {
         use std::os::windows::process::CommandExt;
@@ -261,6 +280,62 @@ pub(crate) fn spawn_installed_desktop(install_root: &std::path::Path) -> std::io
     cmd.spawn().map(|_child| ())
 }
 
+#[cfg(target_os = "macos")]
+pub(crate) fn open_macos_app_detached(app_bundle: &std::path::Path) -> std::io::Result<()> {
+    let mut cmd = std::process::Command::new("/usr/bin/open");
+    cmd.arg(app_bundle);
+    cmd.current_dir(crate::paths::hermes_home());
+    cmd.spawn().map(|_child| ())
+}
+
+#[cfg(target_os = "macos")]
+fn app_bundle_for_exe(exe: &std::path::Path) -> Option<PathBuf> {
+    let app = exe.parent()?.parent()?.parent()?.to_path_buf();
+    if app.extension().and_then(|e| e.to_str()) == Some("app") && app.is_dir() {
+        Some(app)
+    } else {
+        None
+    }
+}
+
+fn desktop_launch_command(
+    exe_path: &std::path::Path,
+    install_root: &std::path::Path,
+) -> tokio::process::Command {
+    #[cfg(target_os = "macos")]
+    {
+        if let Some(app_bundle) = app_bundle_for_exe(exe_path) {
+            let mut cmd = tokio::process::Command::new("/usr/bin/open");
+            cmd.arg(app_bundle);
+            cmd.current_dir(crate::paths::hermes_home());
+            return cmd;
+        }
+    }
+
+    let mut cmd = tokio::process::Command::new(exe_path);
+    cmd.current_dir(exe_path.parent().unwrap_or(install_root));
+    cmd
+}
+
+fn desktop_launch_command_std(
+    exe_path: &std::path::Path,
+    install_root: &std::path::Path,
+) -> std::process::Command {
+    #[cfg(target_os = "macos")]
+    {
+        if let Some(app_bundle) = app_bundle_for_exe(exe_path) {
+            let mut cmd = std::process::Command::new("/usr/bin/open");
+            cmd.arg(app_bundle);
+            cmd.current_dir(crate::paths::hermes_home());
+            return cmd;
+        }
+    }
+
+    let mut cmd = std::process::Command::new(exe_path);
+    cmd.current_dir(exe_path.parent().unwrap_or(install_root));
+    cmd
+}
+
 // ---------------------------------------------------------------------------
 // Bootstrap implementation
 // ---------------------------------------------------------------------------