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/prestigePanel.tsx

@@ -89,6 +89,7 @@ const PrestigePanel = (): JSX.Element => {
     enableNotifications,
     enableSounds,
     toggleAutoPrestige,
+    triggerPrestigeToast,
   } = useGame();
   const [ isPending, setIsPending ] = useState(false);
   const [ result, setResult ] = useState<{
@@ -128,6 +129,7 @@ const PrestigePanel = (): JSX.Element => {
         milestoneRunestones: data.milestoneRunestones,
         runestones:          data.runestones,
       });
+      triggerPrestigeToast();
       if (enableSounds) {
         playSound("prestige");
       }