kernel-config.sh looked for the tree two levels up and build-kernel.sh
did not pass on the tree it had resolved, so a plain
./scripts/build-kernel.sh could configure one tree and build another.
Both resolve <repo>/../linux-7.3.4.
- 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