feat: unify toast styles and add quest/milestone toast notifications

- Merge .codex-toast and .achievement-toast into a single .game-toast class
- Fix storyToast inner class names and replace <button> wrapper with <div>
- Add QuestCompleteToast and QuestFailedToast components
- Add MilestoneToast for prestige, transcendence, and apotheosis events
- Move shared toast container to gameLayout so all toasts stack in one column
- Wire quest detection in GameContext to store full Quest objects for toast names
- Trigger prestige toast from both auto-prestige and manual prestige panel

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

@@ -41,7 +41,7 @@ const ToastItem = ({
   const crystals = achievement.reward?.crystals;
 
   return (
-    <div className="achievement-toast" onClick={handleClick}>
+    <div className="game-toast" onClick={handleClick}>
       <span className="toast-icon">{achievement.icon}</span>
       <div className="toast-content">
         <span className="toast-label">{"Achievement Unlocked!"}</span>
@@ -70,7 +70,7 @@ const AchievementToast = (): JSX.Element | null => {
   }
 
   return (
-    <div className="achievement-toast-container">
+    <>
       {pendingAchievements.map((achievement) => {
         return (
           <ToastItem
@@ -80,7 +80,7 @@ const AchievementToast = (): JSX.Element | null => {
           />
         );
       })}
-    </div>
+    </>
   );
 };