apl: perf — fix quadratic append in permutations, restore queens(8)

apl-permutations was doing (append acc <new-perms>) which is
O(|acc|) and acc grows ~N! big — total cost O(N!²).

Swapped to (append <new-perms> acc) — append is O(|first|)
so cost is O((n+1)·N!_prev) per layer, total O(N!).  q(7)
went from 32s to 12s; q(8)=92 now finishes well within the
300s timeout, so the queens(8) test is restored.

497/497.  Phase 8 complete.

lib/apl/tests/programs.sx

@@ -252,6 +252,8 @@
 
 (apl-test "queens 7 → 40 solutions" (mkrv (apl-queens 7)) (list 40))
 
+(apl-test "queens 8 → 92 solutions" (mkrv (apl-queens 8)) (list 92))
+
 (apl-test "permutations of 3 has 6" (len (apl-permutations 3)) 6)
 
 (apl-test "permutations of 4 has 24" (len (apl-permutations 4)) 24)