add bridge tile for better bridge pathfinding

rtsim/src/rule/npc_ai.rs

@@ -61,7 +61,7 @@ fn path_in_site(start: Vec2<i32>, end: Vec2<i32>, site: &site2::Site) -> PathRes
             TileKind::Empty => 3.0,
             TileKind::Hazard(_) => 50.0,
             TileKind::Field => 8.0,
-            TileKind::Plaza | TileKind::Road { .. } | TileKind::Path => 1.0,
+            TileKind::Plaza | TileKind::Road { .. } | TileKind::Path | TileKind::Bridge => 1.0,
 
             TileKind::Building
             | TileKind::Castle

world/src/site2/mod.rs

@@ -1067,7 +1067,7 @@ impl Site {
         });
 
         site.blit_aabr(aabr, Tile {
-            kind: TileKind::Building,
+            kind: TileKind::Bridge,
             plot: Some(plot),
             hard_alt: None,
         });

world/src/site2/tile.rs

@@ -191,6 +191,7 @@ pub enum TileKind {
     Keep(KeepKind),
     Gate,
     GnarlingFortification,
+    Bridge,
 }
 
 #[derive(Clone, PartialEq)]