feat(build): add preflight package resolution and fws-dnd package

Add preflight package resolution step in build-offi.sh to validate all profile
packages against pacman repositories before mkarchiso execution. This prevents
'target not found' errors during ISO creation by catching missing packages early
with helpful error messages and recovery instructions.

Introduce fws-dnd package (D&D 5e manager for FWS with GTK4 interface) to the
local package build process in setup-aur.sh. Include PKGBUILD definition and
source tarball.

When package resolution fails, the build now exits with clear feedback pointing
users to run setup-aur.sh to build missing dependencies like fws-dnd.

setup-aur.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 # ============================================================
-#  FWS — Build des paquets AUR (winboat-bin) + PKGBUILD locaux (deps Anaconda)
-#  et création du repo pacman local fws-local/.
+#  FWS — Build des paquets AUR (winboat-bin) + PKGBUILD locaux (deps Anaconda,
+#  fws-dnd) et création du repo pacman local fws-local/.
 #
 #  Rejoue-le si tu changes la liste AUR_PACKAGES ou pour
 #  rafraîchir le repo local.
@@ -297,6 +297,7 @@ done
 # --- PKGBUILD locaux FWS (ordre explicite, feuilles d'abord, anaconda dernier) ---
 LOCAL_PKGBUILDS_DIR="$SCRIPT_DIR/pkgbuilds"
 LOCAL_BUILD_ORDER=(
+    fws-dnd
     pykickstart python-productmd python-requests-file python-simpleline
     python-crypt_r python-iso639 python-langtable python-meh python-blivet
     anaconda-widgets anaconda