Document array-valued local variables (statevar type=array with
elem/sizing/capacity), the value-polymorphic expression engine and array
functions, the array.* mutation nodes, accumulate/export unification, and
index-aligned CSV export in TECHNICAL_SPEC §3.8. Note in TODO that panel-logic
(Phase 1) array support is complete while the server-side control-logic port
(Phase 2) remains pending.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
