chore: repo scaffold, READMEs (EN/pt-BR), version pins, source fetch+vendorize scripts

- pins OpenBSD 8.0 tarballs (sha256) and Linux 7.3.4 as the port targets
- scripts/fetch-sources.sh (C3SL primary, cdn fallback), scripts/vendorize.sh
- scripts/{kernel-config,build-kernel}.sh for the VM-lab kernel

.gitignore

@@ -0,0 +1,15 @@
+_vendor/
+out/
+*.o
+*.ko
+*.mod
+*.mod.c
+*.o.d
+*.symvers
+.tmp_versions/
+modules.order
+Module.symvers
+tools/out/
+lab/seeds/
+*.pcap
+*.log