docker: copy conntdb_lib.py into runtime image

keydb.py imports conntdb_lib at startup (for the new 'stats' command),
so the runtime stage of docker/Dockerfile needs the file alongside
keydb.py / keydb_lib.py. Without this the 'docker-test' CI job fails
with ModuleNotFoundError on any keydb.py invocation.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: tridge

docker/Dockerfile

@@ -59,6 +59,7 @@ WORKDIR /app
 COPY --from=builder /app/udpproxy /app/udpproxy
 COPY --from=builder /app/keydb.py /app/keydb.py
 COPY --from=builder /app/keydb_lib.py /app/keydb_lib.py
+COPY --from=builder /app/conntdb_lib.py /app/conntdb_lib.py
 
 # Create data directory for persistent storage
 RUN mkdir -p /app/data