Adds an N-tool for one row in a FAQ list. Collapsed (default):
bold question + chevron-right header. Expanded (expanded=true):
chevron-down + multi-line answer paragraph beneath. Optional
show_divider draws a 1px slate-200 rectangle at the bottom for
visual separation between items (no implicit padding — caller
stacks in a vertical parent).
Wired through all 3 paths (pen-core buildFaqItem + pen-mcp handler
+ apps/web shim + Nitro SERVER_BUILDERS); both parity tests and
the stale-integration guard auto-pick-up the entry. Handler test
covers 5 cases: collapsed default, expanded with answer, expanded
without answer (guards against undefined), show_divider hairline,
bogus parent_id rejection.