fix(guix-iso): align local channel assets and x86_64 bootstrap

steps-guix/guix-1.5.0/patches/build-native-utils-earlier.patch

@@ -16,7 +16,7 @@ index 852fa2d..2dfb6a3 100644
 +    (name name)
 +    (source (bootstrap-origin (package-source pkg)))
 +    (native-inputs (inputs))
-+    (supported-systems '("i686-linux"))
++    (supported-systems '("i686-linux" "x86_64-linux"))
 +    (inputs '())
 +    (propagated-inputs '())
      (arguments

steps-guix/improve/guix-build-iso.sh

@@ -20,6 +20,9 @@ fi
 mkdir -p "${out_dir}"
 
 cp /var/guix/profiles/per-user/root/current-guix/manifest /usr/manifest
+test -d /usr/share/guile/site/3.0/gnu/installer/aux-files || \
+    cp -r /var/lib/guix/local-channels/guix/gnu/installer/aux-files \
+        /usr/share/guile/site/3.0/gnu/installer/
 
 guix system image \
     --system=x86_64-linux \

steps-guix/improve/guix-daemon-and-pull.sh

@@ -320,4 +320,4 @@ if ! guile -c '(use-modules (gnutls)) (if (module-variable (resolve-module (quot
 fi
 
 start_distfiles_http_server
-guix pull --bootstrap -c "${JOBS}" --no-substitutes --channels="${channels_file}" --disable-authentication
+guix pull --system=x86_64-linux --bootstrap -c "${JOBS}" --no-substitutes --channels="${channels_file}" --disable-authentication