Adds `sds pathfind-dump`, an offline corpus of every `(hex, facing)` a walking Mek can reach, read out of MegaMek's own `MovePath` and `isMoveLegal`. Twenty-four cases over two boards - open ground and heavy forest - with three starts each covering both column parities and a hillside, two facings and two MP budgets. Nothing dumps during a match. The tests here are the corpus's own contract: coverage, consistency, a fixed write order, and that the state set for 4 MP is a subset of the set for 6.