Updated Dockerfile, README, and util.rs for Docker support

Dockerfile

@@ -11,7 +11,7 @@ WORKDIR /usr/src/civkit-node
 COPY . .
 
 # Build the application
-RUN cargo build
+RUN cargo build --release --bin=civkitd
 
 # Stage 2: Setup the runtime environment
 FROM ubuntu:latest
@@ -25,6 +25,12 @@ COPY --from=builder /usr/src/civkit-node/target/debug/civkitd /usr/local/bin/civ
 COPY --from=builder /usr/src/civkit-node/target/debug/civkit-cli /usr/local/bin/civkit-cli
 COPY --from=builder /usr/src/civkit-node/target/debug/civkit-sample /usr/local/bin/civkit-sample
 
+# Expose ports
+EXPOSE 50031
+EXPOSE 9735
+EXPOSE 50021
+EXPOSE 18443
+
 # Set the default command to run the main binary
 CMD ["civkitd"]