feat(baseline): add locale generation and rootfs mounting infrastructure

Add locale configuration, systemd service for rootfs mounting, and customization script:

- Add locale.gen to generate en_US.UTF-8 locale required by Anaconda
- Add fws-rootfsbase.service to expose squashfs as /run/rootfsbase for Anaconda LiveOS payload detection
- Add customize_airootfs.sh to run locale-gen during image build
- Add python-iso639 0.1.4 PKGBUILD (local package with correct find() API)
- Add python-langtable 0.0.71 PKGBUILD (local package with list_common_languages())
- Remove python-iso639 and python-langtable from AUR packages due to version/API incompatibilities
- Update LOCAL_BUILD_ORDER to include new local packages

setup-aur.sh

@@ -17,7 +17,11 @@ trap 'rc=$?; echo -e "\033[0;31m[ERR] Échec (setup-aur.sh) ligne $LINENO, code
 #   - python-*         : deps Anaconda présentes dans l'AUR (deps officielles only)
 # python-blivet est packagé en LOCAL (pkgbuilds/, patché sans libselinux).
 # gnome-kiosk (WM de la session GUI) est différé au chantier C.
-AUR_PACKAGES=(libxmlrpc satyr libreport winboat-bin python-langtable python-pid python-iso639 python-xkbregistry python-requests-ftp)
+# NB : python-iso639 RETIRÉ de l'AUR (mauvais projet homonyme, API sans find()) →
+# packagé en LOCAL (pkgbuilds/python-iso639, projet PyPI « iso639 » 0.1.4).
+# NB : python-langtable RETIRÉ de l'AUR (figé 0.0.51, sans list_common_languages) →
+# packagé en LOCAL (pkgbuilds/python-langtable, 0.0.71).
+AUR_PACKAGES=(libxmlrpc satyr libreport winboat-bin python-pid python-xkbregistry python-requests-ftp)
 DISTRO_NAME="${ARCH_WSL_DISTRO:-Arch}"
 
 RED='\033[0;31m'; GREEN='\033[0;32m'; YELLOW='\033[1;33m'
@@ -273,7 +277,8 @@ done
 LOCAL_PKGBUILDS_DIR="$SCRIPT_DIR/pkgbuilds"
 LOCAL_BUILD_ORDER=(
     pykickstart python-productmd python-requests-file python-simpleline
-    python-crypt_r python-meh python-blivet anaconda-widgets anaconda
+    python-crypt_r python-iso639 python-langtable python-meh python-blivet
+    anaconda-widgets anaconda
 )
 BUILT_LOCAL=()