Fourth master: dwarves get their own side so the yellow AI works; yellow colours and texts; AI cores use the player's throne and heart in their colour

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

src/game.rs

@@ -299,7 +299,7 @@ pub struct Ent {
     #[serde(default)]
     pub pay_t: f32, // seconds until the creature goes for its wage
     #[serde(default)]
-    pub side: u8, // 0 player, 2 and 3 rival masters (heroes: see side())
+    pub side: u8, // 0 player, 2..=4 the other masters, 6 dwarves (heroes: see side())
     #[serde(default)]
     pub target: Option<u8>, // attackers: side whose core (or gate) they march on
     #[serde(default)]
@@ -409,7 +409,7 @@ impl Ent {
     }
     // a unit of a rival master
     pub fn rival(&self) -> bool {
-        !self.hero && (self.side == 2 || self.side == 3)
+        !self.hero && (2..=4).contains(&self.side)
     }
     // a dwarf of a dwarf cave (neutral, never an opponent for victory)
     pub fn dwarf(&self) -> bool {