Server was sending visible_tiles without tile type data, so the client
could not distinguish floor from wall in live mode. Add TileKind enum
(Floor/Wall/Door/Object) to VisibleTile, populated from WalkabilityMap
in the NaturalVision perception query. Update test fixtures to include
the new field. Uses #[serde(default)] for backward compatibility.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>