A 2-node graph has no degree>=2 candidates, so farthestPointAnchors
returns empty before any Dijkstra runs and never reaches the overflow
throw. Node 1 on a 3-node path is a candidate, so the selection pass
actually exercises the law.
Hand-computed vectors for the pure landmark compute core: deterministic
degree-filtered farthest-point anchors, exact integer quanta
(floor(2.55/0.1)=25, two edges=50), 0xFFFF sentinel + self-cell laws,
oneway asymmetry, the 65000-quantum overflow throw, and the 5x5-grid
corner-to-corner 264-quanta vector with coverage 1.0.