dist/*.c and *.elh are elc transpiler output. CI's header-gen step still
greps dist/*.c, so they stay tracked, but a single soul change regenerates
~57k lines of dist/neuron.c + dist/soul.c that bury the real source diff and
poison both human and agent PR review. Mark them -diff + linguist-generated so
PRs show only the real changes. Build pipeline unchanged.