Complete the overworld foundation

Port forced movement (turn delays, bumps, ice, currents, pits), dynamic
return warps, elevators, Surf, Cut, Strength and cycling rules, working
map blocks with changeblock/changemapblocks, and the remaining NPC
movement types and movement commands.

Add tileset animation from the ROM's command tables, grass sprite
priority and special map palettes; room decorations with ownership, the
bedroom PC and save migration; and Key Items access to the Bicycle.

Fourteen original-engine traces compare positions, facing, actors, event
flags and scripted poses. Tile animation matches original VRAM for four
tilesets, and LoadMapPals matches 192 palette cases. skyfall_top now
keeps the $60 sprite offset its step function leaves behind.

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

tests/foundation-fixture.ts

@@ -0,0 +1,26 @@
+import { CrystalAssets } from "../src/game/rom/assets";
+import { GameWorld } from "../src/game/world/world";
+import { OW } from "../src/game/world/constants";
+
+export function foundationFixture(
+  assets: CrystalAssets,
+  room: boolean | "poster",
+) {
+  const world = new GameWorld(
+    assets,
+    () => new Date("2026-09-22T12:00:00"),
+    () => 0,
+  );
+  world.state.scenes["24:4"] = 1;
+  world.state.bag.keyItems.push(OW.BICYCLE);
+  const save = world.save();
+  world.restore({
+    ...save,
+    map: room ? "24:7" : "24:4",
+    x: room === "poster" ? 6 : room ? 2 : 9,
+    y: room === "poster" ? 1 : room ? 2 : 6,
+    direction: "up",
+    objects: [],
+  });
+  return world;
+}