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.

pkgbuilds/fws-dnd/PKGBUILD

@@ -0,0 +1,31 @@
+# Maintainer: FWS
+pkgname=fws-dnd
+pkgver=2.0.0
+pkgrel=1
+pkgdesc="Gestionnaire D&D 5e pour FWS (GTK4) : dés, créateur de personnage (règles officielles), grimoire, sessions, tracker de combat"
+arch=('any')
+url="https://fws.local/fws-dnd"
+license=('MIT')
+depends=('python' 'python-gobject' 'gtk4')
+source=("${pkgname}-${pkgver}.tar.gz")
+sha256sums=('SKIP')
+
+package() {
+  cd "${srcdir}/${pkgname}-${pkgver}"
+
+  # Module Python (application GTK4)
+  install -d "${pkgdir}/usr/share/${pkgname}"
+  cp -r gui/fwsdnd "${pkgdir}/usr/share/${pkgname}/"
+  # pas de bytecode pré-généré dans le paquet
+  find "${pkgdir}/usr/share/${pkgname}" -name '__pycache__' -type d -exec rm -rf {} +
+
+  # Exécutable
+  install -Dm755 bin/fws-dnd "${pkgdir}/usr/bin/fws-dnd"
+
+  # Intégration bureau
+  install -Dm644 fws-dnd.desktop "${pkgdir}/usr/share/applications/fws-dnd.desktop"
+  install -Dm644 fws-dnd.svg "${pkgdir}/usr/share/icons/hicolor/scalable/apps/fws-dnd.svg"
+
+  # Documentation
+  install -Dm644 README.md "${pkgdir}/usr/share/doc/${pkgname}/README.md"
+}