feat: vampire boss panel and thralls panel with combat simulation

Implements VampireBossPanel (zone filtering, HP bar, battle modal with
rewards/casualties) and VampireThrallsPanel (batch buy with geometric
cost scaling). Wires challengeVampireBoss, dismissVampireBattle, and
buyVampireThrall into GameContext with correct sort-key ordering.

apps/web/src/components/game/gameLayout.tsx

@@ -54,7 +54,9 @@ import { StoryToast } from "./storyToast.js";
 import { TranscendencePanel } from "./transcendencePanel.js";
 import { UpgradePanel } from "./upgradePanel.js";
 import { VampireAchievementsPanel } from "./vampireAchievementsPanel.js";
+import { VampireBossPanel } from "./vampireBossPanel.js";
 import { VampireQuestsPanel } from "./vampireQuestsPanel.js";
+import { VampireThrallsPanel } from "./vampireThrallsPanel.js";
 import { VampireZonesPanel } from "./vampireZonesPanel.js";
 
 type Mode = "mortal" | "goddess" | "vampire";
@@ -486,9 +488,7 @@ const GameLayout = (): JSX.Element => {
             }
             {activeMode === "vampire"
             && activeVampireTab === "vampire-bosses"
-              && <div className="vampire-placeholder">
-                <p>{"🩸 Vampire Bosses coming soon..."}</p>
-              </div>
+              && <VampireBossPanel />
             }
             {activeMode === "vampire"
             && activeVampireTab === "vampire-quests"
@@ -496,9 +496,7 @@ const GameLayout = (): JSX.Element => {
             }
             {activeMode === "vampire"
             && activeVampireTab === "thralls"
-              && <div className="vampire-placeholder">
-                <p>{"🧟 Thralls coming soon..."}</p>
-              </div>
+              && <VampireThrallsPanel />
             }
             {activeMode === "vampire"
             && activeVampireTab === "vampire-equipment"