fix hadolint errors

.devcontainer/resources/devcontainer-Dockerfile

@@ -7,6 +7,7 @@
 # Open and wide to avoid permission issues during development allowing max
 # flexibility.
 
+# hadolint ignore=DL3006
 FROM runner AS netalertx-devcontainer
 ENV INSTALL_DIR=/app
 
@@ -20,10 +21,15 @@ ENV PYDEVD_DISABLE_FILE_VALIDATION=1
 COPY .devcontainer/resources/devcontainer-overlay/ /
 USER root
 # Install common tools, create user, and set up sudo
+
 RUN apk add --no-cache git nano vim jq php83-pecl-xdebug py3-pip nodejs sudo gpgconf pytest \
     pytest-cov zsh alpine-zsh-config shfmt github-cli py3-yaml py3-docker-py docker-cli docker-cli-buildx \
     docker-cli-compose
 
+# Install hadolint (Dockerfile linter)
+RUN curl -L https://github.com/hadolint/hadolint/releases/latest/download/hadolint-Linux-x86_64 -o /usr/local/bin/hadolint && \
+    chmod +x /usr/local/bin/hadolint
+
 RUN install -d -o netalertx -g netalertx -m 755 /services/php/modules && \
     cp -a /usr/lib/php83/modules/. /services/php/modules/ && \
     echo "${NETALERTX_USER} ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers