New Supabase table neuron_config keyed on (key, scope) with jsonb
value column. Web tier reads chat.model via /api/demo with 60s TTL
caching, passes to soul via dharma envelope payload.model. No more
revision-rollout-per-model-swap.
Admin read endpoint at /api/admin/config gated by NEURON_ADMIN_TOKEN.
Write surface and Realtime subscription land in Phase 2.
Backlog: bl-6eb51893
Will Anderson