ludic.npc (17.7): a person's fallback is a fact

A step round what is in the way, a target planned again after twenty seconds without progress, and a target given up are each pushed as NPC_F_STUCK (how, x, z), so the game can see where the way failed a person. The lake test expects one when a walker turns back from the water; the way test expects none when the world gives the way.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/ludic.npc/tests/way_test.ludic

@@ -78,5 +78,7 @@ program NpcWayTest {
     expect_eq(p.act, NPCA_SIT)
     expect(npc_d(p.x, p.z, 38.0, -25.0) < 1.3)
     expect(way_test_st.asked > 5)
+    let fs = q_drain(npc_facts(npc_st))
+    for i in 0 .. len(fs) { expect(fs[i].what != NPC_F_STUCK) }
   }
 }