iso: calamares from [tanin] (AUR rebuild); document the build step

- packages.x86_64: calamares enabled (served from [tanin])
- finish/build-tanin-repo.sh: add calamares to the AUR rebuild list
- BUILD.md + manifest: calamares rebuild step + status

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packaging/build-tanin-repo.sh

@@ -17,7 +17,7 @@ mkdir -p "$OUT"
 
 OWN_SIMPLE=(tanin-greet tanin-libadwaita tanin-setup tanin-eww tanin-desktop)
 OWN_BUILD=(taninux)
-AUR_REBUILD=(eww-git tiramisu-git waypaper)
+AUR_REBUILD=(eww-git tiramisu-git waypaper calamares)
 
 build() {
   local p="$1"

packaging/finish-tanin-repo.sh

@@ -16,9 +16,9 @@ sudo pacman -S --needed --noconfirm python-build python-installer python-hatchli
 ( cd "$HERE/taninux" && makepkg -sf --noconfirm ) \
   && cp "$HERE/taninux/"*.pkg.tar.zst "$OUT/" && echo "   ok" || echo "   FAILED (taninux)"
 
-echo "==> AUR rebuilds: eww-git tiramisu-git waypaper"
+echo "==> AUR rebuilds: eww-git tiramisu-git waypaper calamares"
 tmp="$(mktemp -d)"
-for p in eww-git tiramisu-git waypaper; do
+for p in eww-git tiramisu-git waypaper calamares; do
   echo "  -- $p"
   if git clone --depth=1 "https://aur.archlinux.org/$p.git" "$tmp/$p" >/dev/null 2>&1 \
      && ( cd "$tmp/$p" && makepkg -sf --noconfirm ); then