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/styles.css

@@ -1432,20 +1432,6 @@ body {
   z-index: 200;
 }
 
-.achievement-toast {
-  align-items: center;
-  animation: slide-in-right 0.35s ease-out;
-  background: var(--colour-surface);
-  border: 1px solid var(--colour-gold);
-  border-radius: var(--radius);
-  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.4);
-  cursor: pointer;
-  display: flex;
-  gap: 0.75rem;
-  max-width: 280px;
-  padding: 0.75rem 1rem;
-}
-
 .toast-icon {
   font-size: 1.5rem;
   flex-shrink: 0;
@@ -2481,8 +2467,8 @@ body {
   padding: 0.6rem 0.75rem;
 }
 
-/* Codex toast — uses a different accent from achievement toast */
-.codex-toast {
+/* Unified game toast — essence-coloured border used by all in-game notifications */
+.game-toast {
   align-items: center;
   animation: slide-in-right 0.35s ease-out;
   background: var(--colour-surface);