Room levels 2 and 3, researched in the library: a quarter better each, brighter, with gold trim

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

src/map.rs

@@ -352,6 +352,8 @@ pub struct Map {
     pub visible: Vec<bool>, // fog of war: tiles in sight right now
     #[serde(default, with = "crate::fog::bits")]
     pub sky: Vec<bool>, // tiles above ground (daylight, grass); empty: all underground
+    #[serde(default)]
+    pub upgrades: Vec<(u8, u8, u8)>, // researched room levels for the look: (master side, room index, level)
 }
 
 fn default_size() -> usize {
@@ -604,7 +606,7 @@ impl Map {
                 tl.hp = 6.0;
             }
         }
-        Map { w, h, t, core, portals, legacy_portal: None, gate, treasures, explored: Vec::new(), visible: Vec::new(), sky: Vec::new() }
+        Map { w, h, t, core, portals, legacy_portal: None, gate, treasures, explored: Vec::new(), visible: Vec::new(), sky: Vec::new(), upgrades: Vec::new() }
     }
 
     // Carves a meandering river; the player's area, the core and portals stay dry.