chore: rebrand backone names, add lint gate + agent docs

- CI: build/validate use backone selftest + binary names, add lint.yml
- make-*.mk: emit/install backone binaries, drop zerotier-one paths
- doc/debian/ext.installfiles: backone manpages, service, init, te
- rule-compiler: npm test runs test.js; attic world planet files
- AGENTS.md repository guidelines, tools/lint.sh changed-lines gate
- gitignore: /backone-selftest, *.gcno, *.gcda

Dockerfile.ci

@@ -6,16 +6,17 @@ RUN apt-get update -qq && apt-get -qq install make clang
 COPY . .
 RUN /usr/bin/make
 RUN echo $PWD
-RUN cp zerotier-one /usr/sbin
+RUN cp backone /usr/sbin
 
 FROM ubuntu:21.04
 
-COPY --from=stage /zerotier-one /usr/sbin
-RUN ln -sf /usr/sbin/zerotier-one /usr/sbin/zerotier-idtool
-RUN ln -sf /usr/sbin/zerotier-one /usr/sbin/zerotier-cli
+COPY --from=stage /backone /usr/sbin
+RUN ln -sf /usr/sbin/backone /usr/sbin/backone-idtool
+RUN ln -sf /usr/sbin/backone /usr/sbin/backone-cli
 
 RUN echo "${VERSION}" > /etc/zerotier-version
-RUN rm -rf /var/lib/zerotier-one
+RUN rm -rf /var/lib/backone
+ENV ZEROTIER_HOME=/var/lib/backone ZT_PID_FILE=backone.pid ZT_PORT_FILE=backone.port ZT_DAEMON=/usr/sbin/backone ZT_CLI=backone-cli
 
 
 RUN apt-get -qq update