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/storyToast.tsx

@@ -45,13 +45,13 @@ const StoryToastItem = ({
   }
 
   return (
-    <button className="achievement-toast" onClick={handleClick} type="button">
-      <span className="achievement-toast-icon">{"📖"}</span>
-      <div className="achievement-toast-content">
-        <span className="achievement-toast-label">{"✨ New Chapter!"}</span>
-        <span className="achievement-toast-name">{chapter.title}</span>
+    <div className="game-toast" onClick={handleClick}>
+      <span className="toast-icon">{"📖"}</span>
+      <div className="toast-content">
+        <span className="toast-label">{"✨ New Chapter!"}</span>
+        <span className="toast-name">{chapter.title}</span>
       </div>
-    </button>
+    </div>
   );
 };
 
@@ -65,11 +65,11 @@ const StoryToast = (): JSX.Element | null => {
     return null;
   }
   return (
-    <div className="achievement-toast-container">
+    <>
       {pendingChapterIds.map((id) => {
         return <StoryToastItem chapterId={id} key={id} />;
       })}
-    </div>
+    </>
   );
 };