Build each package in an isolated container

tests/build-isolation.Dockerfile

@@ -0,0 +1,11 @@
+# Only the build runner is under test; source-free fixtures need no Omarchy
+# bootstrap, signing key, mirror, or production repository.
+FROM archlinux:base-devel
+RUN pacman -Syu --noconfirm git jq sudo && \
+    useradd -m -u 1000 builder && \
+    echo 'builder ALL=(ALL) NOPASSWD: ALL' > /etc/sudoers.d/builder && \
+    printf '#!/bin/bash\nexec /usr/bin/pacman --ask 4 "$@"\n' > /usr/local/bin/pacman-for-makepkg && \
+    chmod +x /usr/local/bin/pacman-for-makepkg && \
+    mkdir /src && chown builder:builder /src
+USER builder
+WORKDIR /src