added build test and enabled nix

.devcontainer/Dockerfile

@@ -49,9 +49,14 @@ RUN dnf upgrade --refresh -y && \
         tmux \
         tar \
         htop \
+        nix \
         nodejs && \
     dnf clean all
 
+# Enable Nix flakes
+RUN mkdir -p /root/.config/nix \
+    && echo 'experimental-features = nix-command flakes' > /root/.config/nix/nix.conf
+
 RUN dnf config-manager addrepo --from-repofile=https://cli.github.com/packages/rpm/gh-cli.repo && dnf install gh --repo gh-cli -y && dnf clean all
 
 RUN mkdir -p -m 0700 ~/.ssh && ssh-keyscan github.com >> ~/.ssh/known_hosts

.github/workflows/pr-build-check.yml

@@ -0,0 +1,19 @@
+name: PR Build Check
+
+on:
+  pull_request:
+    paths:
+      - '.devcontainer/Dockerfile'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Build image
+        uses: docker/build-push-action@v7
+        with:
+          context: .
+          file: .devcontainer/Dockerfile
+          push: false