docker: add container HEALTHCHECK for CodeChecker web

Use Python stdlib to probe the built-in /live endpoint without adding curl.
Fixes #4564

Author: 0rlych1kk4

web/docker/Dockerfile

@@ -139,6 +139,9 @@ RUN chmod 755 /usr/local/bin/wait-for
 
 EXPOSE 8001
 
+HEALTHCHECK --interval=30s --timeout=5s --start-period=20s --retries=3 \
+  CMD python3 -c "import urllib.request; urllib.request.urlopen('http://127.0.0.1:8001/live', timeout=3).read()" || exit 1
+
 ENTRYPOINT ["/tini", "--", "/usr/local/bin/entrypoint.sh"]
 
 CMD ["CodeChecker", "server", "--workspace", "/workspace", "--not-host-only"]