Adds citer-both-in-target to the shared fixture, the first row in file (and
row-order) to cite "dup-key" through Design - both leaf_a and leaf_b at that
key are in Design's declared target, unlike citer_narrow's narrow_ref above
it (only ever one in-target candidate). Adds the matching vector case to
both runtimes' case lists and regenerates both written vector files
(CULTNET_WRITE_VECTORS=1), so cross-runtime agreement on this shape is
pinned by the parity check, not just asserted per-runtime.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>