fix(nix): run installer via su instead of sudo to avoid PAM failures in minimal containers

https://chatgpt.com/share/69662b41-2768-800f-a721-292889889547

scripts/installation/arch/aur-builder-setup.sh

@@ -38,11 +38,7 @@ echo "[aur-builder-setup] Configuring sudoers for aur_builder..."
 ${ROOT_CMD} bash -c "echo '%aur_builder ALL=(ALL) NOPASSWD: /usr/bin/pacman' > /etc/sudoers.d/aur_builder"
 ${ROOT_CMD} chmod 0440 /etc/sudoers.d/aur_builder
 
-if command -v sudo >/dev/null 2>&1; then
-  RUN_AS_AUR=(sudo -u aur_builder bash -lc)
-else
-  RUN_AS_AUR=(su - aur_builder -c)
-fi
+RUN_AS_AUR=(su - aur_builder -s /bin/bash -c)
 
 echo "[aur-builder-setup] Ensuring yay is installed for aur_builder..."
 

scripts/nix/lib/install.sh

@@ -49,11 +49,7 @@ install_nix_with_retry() {
   if [[ -n "$run_as" ]]; then
     chown "$run_as:$run_as" "$installer" 2>/dev/null || true
     echo "[init-nix] Running installer as user '$run_as' ($mode_flag)..."
-    if command -v sudo >/dev/null 2>&1; then
-      sudo -u "$run_as" bash -lc "sh '$installer' $mode_flag"
-    else
-      su - "$run_as" -c "sh '$installer' $mode_flag"
-    fi
+    su - "$run_as" -s /bin/bash -c "bash -lc \"sh '$installer' $mode_flag\""
   else
     echo "[init-nix] Running installer as current user ($mode_flag)..."
     sh "$installer" "$mode_flag"