Every master of a match gets an own portal beside the dungeon

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

src/rival.rs

@@ -97,25 +97,7 @@ impl Game {
     pub fn add_rival(&mut self, side: u8, cx: i32, cy: i32, difficulty: u8) {
         let core = (cx - 1, cy - 1);
         self.carve_master_area(side, core);
-        // his own portal beside the dungeon (if there is room)
-        let owner = Owner::of_side(side);
-        let (px, py) = (core.0 + 6, core.1);
-        if px + 3 < mw() as i32 - 2 && py >= 2 && py + 3 < mh() as i32 - 2 {
-            for y in py..py + 3 {
-                for x in px..px + 3 {
-                    let t = &mut self.map.t[idx(x, y)];
-                    if !matches!(t.kind, Kind::Core | Kind::Gate) {
-                        t.kind = Kind::Portal;
-                        t.owner = owner;
-                        t.gold = 0;
-                        t.reinforced = false;
-                    }
-                }
-            }
-            if !self.map.portals.contains(&(px, py)) {
-                self.map.portals.push((px, py));
-            }
-        }
+        self.add_master_portal(side, core);
         self.rivals.push(Rival { side, core, hp: RIVAL_CORE_HP, alive: true, radius: 5, grow_t: 20.0, spawn_t: 5.0, attack_t: 0.0, difficulty, power: 0.0, gift_t: PARTNER_GIFT_EVERY, think_t: 2.0, attacking: false, army0: 0.0 });
         self.adopt_master(side, core, difficulty, true);
     }