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>

README.md

@@ -12,7 +12,9 @@ North of Cherrygrove, Route 30's trainers battle you. Bug Catcher Don spots you
 
 Mr. Pokémon gives you the Mystery Egg, and Professor Oak gives you the Pokédex. Your rival challenges you in Cherrygrove on the way back, and Elm's aide gives you Poké Balls. Back on Route 29, the Dude shows you how to catch Pokémon. From then on, open PACK in a wild battle to throw a Poké Ball. Caught Pokémon join your party, and you can give them a nickname.
 
-Route 31 and beyond, the PC, party and bag menus, other items in battle, decorations and audio are still being ported. Catching with six Pokémon in your party needs the PC and is refused for now. Unported neighboring areas appear at the edges but cannot be entered yet.
+Use Start or Select for Key Items, including the Bicycle when owned. The bedroom PC lets you arrange owned decorations, and the poster opens the Town Map.
+
+Route 31 and beyond, PC storage, full party and bag menus, other items in battle and audio are still being ported. Catching with six Pokémon in your party needs the PC and is refused for now. Unported neighboring areas appear at the edges but cannot be entered yet.
 
 ## Run