Build each package in an isolated container

.github/workflows/test.yml

@@ -7,6 +7,20 @@ on:
   workflow_dispatch:
 
 jobs:
+  build-isolation:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - name: Prepare fixture builder
+        run: docker build -t omarchy-build-isolation-test -f tests/build-isolation.Dockerfile tests
+      - name: Verify isolated builds with real pacman transactions
+        env:
+          CONTAINER_ENGINE: docker
+          TEST_BUILDER_IMAGE: omarchy-build-isolation-test
+        run: tests/build-isolation.sh
+
   self-tests:
     runs-on: ubuntu-latest