feat(anaconda): integrate anaconda installer with openbox and add licensing documentation

Add Anaconda installer integration to FWS live environment:

- Implement Anaconda launcher in .xinitrc with comprehensive error logging and debugging support
- Add anaconda and anaconda-widgets packages to baseline and releng ISO configs
- Fix anaconda-widgets PKGBUILD: replace gladeui with glib2-devel, disable Glade module
- Update anaconda PKGBUILD with improved dependencies and build configuration
- Add python-blivet PKGBUILD with detailed dependency documentation

Enhance documentation and branding:

- Expand AUTHORS.rst to clarify FWS vs archiso authorship and licensing
- Update CONTRIBUTING.rst with inbound=outbound licensing policy and DCO requirements
- Extend README.md with comprehensive legal basis table and licensing checklist
- Remove Arch Linux references from MOTD and update to FWS GitHub project page
- Fix fastfetch.sh to avoid read-only variable conflict in zsh
- Add xterm to packages for installer debugging

All changes maintain GPL-3.0-or-later compliance and improve GPL offer transparency.

configs/releng/airootfs/etc/profile.d/fastfetch.sh

@@ -1,5 +1,9 @@
 #!/usr/bin/env bash
-status=$?
-if [ "${status}" -eq 0 ]; then
+# NB : ce fichier est SOURCÉ par le shell de login (zsh sur le live), pas exécuté
+# → le shebang est ignoré. En zsh « status » est une variable spéciale EN LECTURE
+# SEULE (alias de $?) : s'y affecter casse (« read-only variable: status »).
+# On utilise donc un autre nom.
+_fastfetch_rc=$?
+if [ "${_fastfetch_rc}" -eq 0 ]; then
     fastfetch
 fi