Add docker file.

Dockerfile

@@ -0,0 +1,28 @@
+FROM node:20.12.1-bullseye-slim
+
+
+WORKDIR /excalidraw-brute-export-cli
+
+RUN apt-get -y update && apt-get -y --no-install-recommends install bash && \
+  apt-get -y clean && \
+  apt-get -y autoremove && \
+  rm -rf /var/lib/apt/lists/* && \
+  useradd -m -d /home/user -s /bin/bash user && \
+  mkdir -p /home/user/.local && \
+  chown -R user:user /excalidraw-brute-export-cli /home/user/.local && \
+  chmod -R a+wrX /excalidraw-brute-export-cli
+
+COPY --chown=user:user . /excalidraw-brute-export-cli
+USER user
+ENV NPM_CONFIG_PREFIX=/home/user/.npm-global
+ENV PATH=/home/user/.npm-global/bin:$PATH
+WORKDIR /excalidraw-brute-export-cli
+RUN npm install -g .
+
+# This is where the user will mount their data to.
+WORKDIR /data
+
+ENTRYPOINT ["npx", "excalidraw-brute-export-cli"]
+CMD ["--help"]
+HEALTHCHECK --interval=30s --timeout=10s --retries=3 \
+  CMD npx excalidraw-brute-export-cli --version || exit 1