- A* pathfinding for actor (find_path in actors.rs)
- Right-click sets target (actor_goto), finds ground below air clicks
- Actor follows path with horizontal velocity + jumping
- Step-up: actor climbs 1-4px small edges/obstacles
- Jump height limited to 40px in pathfinding (avoids unreachable targets)
- Powder displacement when walking through sand/dirt
- Actor collision: solids block, powders pass-through
- Fallback: direct movement if no path found