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

ext/installfiles/linux/backone.te

@@ -0,0 +1,14 @@
+
+module backone 1.0;
+
+require {
+	type unconfined_t;
+	type initrc_t;
+	class memprotect mmap_zero;
+}
+
+#============= initrc_t ==============
+allow initrc_t self:memprotect mmap_zero;
+
+#============= unconfined_t ==============
+allow unconfined_t self:memprotect mmap_zero;