Builds all boards (qemu, pc, pi4, pi5, milkv) in parallel. Installs cross-compilers (aarch64-linux-gnu, riscv64-linux-gnu) and clang-18 for the aarch64 loader. Packs ISO (amd64/aarch64) and GPT image (riscv64). On master push, publishes to Nexus starshipos-releases using Maven coordinates org.f18:kernel:<version>-<sha>:<board> and org.f18:starforth:<version>-<sha>:<board>. CROSS_COMPILE wired into StarForth Makefile via mk/boards.mk so make T=pi4 picks up aarch64-linux-gnu-gcc automatically. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>