Add script to inject environment variables in Dockerfile

- Created a start.sh script to set environment variables for the application.
- Updated CMD to execute the new script instead of directly serving the build.

worklenz-frontend/Dockerfile

@@ -16,5 +16,16 @@ WORKDIR /app
 RUN npm install -g serve
 
 COPY --from=build /app/build /app/build
+
+# Create a script to inject environment variables
+RUN echo '#!/bin/sh\n\
+cat > /app/build/env.js << EOL\n\
+window.env = {\n\
+  VITE_API_URL: "${VITE_API_URL}"\n\
+};\n\
+EOL\n\
+exec serve -s build -l 5000' > /app/start.sh && \
+chmod +x /app/start.sh
+
 EXPOSE 5000
-CMD ["serve", "-s", "build", "-l", "5000"]
+CMD ["/app/start.sh"]