fix(simulation): add TileKind to VisibleTile wire protocol (#412)

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>

server/src/bridge/types.rs

@@ -73,7 +73,7 @@ pub enum FacingDirection {
     Northwest,
 }
 
-/// A tile visible to the observer with its visibility quality
+/// A tile visible to the observer with its visibility quality and type
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct VisibleTile {
     pub x: i32,
@@ -81,6 +81,20 @@ pub struct VisibleTile {
     pub z: i32,
     /// Which vision cone sector this tile falls in (D-015)
     pub visibility: VisibilitySector,
+    /// Tile type for client rendering (floor, wall, door, object)
+    #[serde(default)]
+    pub tile_kind: TileKind,
+}
+
+/// Tile type for rendering. Derived from WalkabilityMap on the server side.
+/// v0.1: Floor (walkable) and Wall (blocked). Door and Object for future use.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default, Serialize, Deserialize)]
+pub enum TileKind {
+    #[default]
+    Floor,
+    Wall,
+    Door,
+    Object,
 }
 
 /// Vision cone sectors per D-015.