feat: CL builds use same animal name, show LISP tag on boot screen
- CL variant inherits the C build's animal name instead of "cl-<hash>"
- /etc/ac-build metadata file written during docker-build (name, hash, ts, variant)
- CL boot splash shows build name at bottom center and golden "LISP" tag top-right
- AC_BUILD_VARIANT=cl passed to CL Docker builds
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>