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/world-driver.ts

@@ -96,7 +96,8 @@ export function findPath(
   throw new Error(`No route to ${targetX},${targetY}`);
 }
 
-/** Walk to a tile, settling any scene that a step triggers. */
+/** Walk to a tile, settling any scene that a step triggers. A roaming NPC
+ * that steps into the way is waited out, then the route is planned again. */
 export function walkTo(
   world: GameWorld,
   targetX: number,
@@ -104,12 +105,26 @@ export function walkTo(
   answers: (number | string)[] = [],
 ): string[] {
   const shown: string[] = [];
-  for (const direction of findPath(world, targetX, targetY)) {
-    if (!world.move(direction))
-      throw new Error(
-        `Blocked moving ${direction} at ${world.x},${world.y}: ${world.notice}`,
-      );
-    shown.push(...settle(world, answers));
+  for (let attempt = 0; attempt < 20; attempt++) {
+    let blocked = false;
+    for (const direction of findPath(world, targetX, targetY)) {
+      if (!world.move(direction)) {
+        const [, dx, dy] = DIRECTIONS.find(([name]) => name === direction)!;
+        const blocker = world
+          .objects()
+          .some((object) => object.x === world.x + dx && object.y === world.y + dy);
+        if (!blocker)
+          throw new Error(
+            `Blocked moving ${direction} at ${world.x},${world.y}: ${world.notice}`,
+          );
+        for (let tick = 0; tick < 64; tick++) world.tick();
+        blocked = true;
+        break;
+      }
+      shown.push(...settle(world, answers));
+    }
+    // A warp target leaves the map, so a completed path is the success test.
+    if (!blocked) return shown;
   }
-  return shown;
+  throw new Error(`Could not reach ${targetX},${targetY}`);
 }