Let NPCs roam as HandleNPCStep does

- Random walks and spins from SpriteMovementData, with random sleeps.
- CanObjectMoveInDirection: side walls, land, objects' current and
  previous tiles, the radius (stored plus one) and the screen edge.
- Objects freeze while text is open and during applymovement, and
  return home when both they and their home leave the object window.
- Wandering positions are not saved; test helpers replan around NPCs.

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

tests/native.test.ts

@@ -320,8 +320,9 @@ describe.skipIf(!existsSync(romPath))(
       expect(pages).toContain("It's dangerous to\ngo out without a\nPOKéMON!");
       // The teacher runs over and leads the player back east.
       expect([world.x, world.y, world.direction]).toEqual([5, 8, "right"]);
+      // Back home, SPRITEMOVEDATA_SPINRANDOM_SLOW spins her again at once.
       const teacher = world.objects().find((object) => object.id === 2)!;
-      expect([teacher.x, teacher.y, teacher.direction]).toEqual([6, 8, "left"]);
+      expect([teacher.x, teacher.y]).toEqual([6, 8]);
       expect(world.save().events).toEqual(events);
       walkTo(world, 2, 2);
       expect(world.move("right")).toBe(false);