Wood: giant mushrooms underground, felled by imps; wooden bridges and doors cost wood

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/wilds.rs

@@ -71,6 +71,8 @@ impl Game {
             }
             self.carve_cavern(x, y, &keep, &mut rng);
         }
+        // giant mushrooms in the open: the underground's little wood
+        self.grow_mushrooms(seed);
     }
 
     // a cavern: a few overlapping blobs, ragged edges