feat: soundboard, toast notifications, robust JSON parsing

Soundboard (Web Audio API):
- 8 ambient loops: rain, wind, fire, ocean, forest, tavern, thunder, cave
- 8 one-shot SFX: sword, bow, spell, door, coins, horn, dice, footsteps
- Brown noise generation for ambient textures
- Oscillator-based SFX with frequency sweeps
- Volume slider, active state indicators with pulsing dot
- Stop All button when ambients are playing
- Toast notifications on SFX trigger

Toast notification system:
- Zustand-based store with auto-dismiss (4s)
- 4 types: success, error, info, warning
- Slide-in animation from top-right
- Dismissible with × button
- Integrated into App shell

JSON parsing (all AI components):
- Shared lib/llm-parse.ts with extractJson, parseLlmJson, flattenValue, ensureArray
- Strips markdown code fences before parsing
- Handles nested objects where strings expected
- All 5 AI components use parseLlmJson instead of raw regex
- All prompts explicitly request raw JSON with no fences
- ItemForge shows raw response in <details> on parse failure

Full production build passing

src/App.tsx

@@ -26,6 +26,8 @@ import { CalendarWidget } from "./components/CalendarWidget";
 import { WorldBuilder } from "./components/WorldBuilder";
 import { ItemForge } from "./components/ItemForge";
 import { QuestDesigner } from "./components/QuestDesigner";
+import { Soundboard } from "./components/Soundboard";
+import { ToastContainer } from "./components/Toast";
 
 export type View =
   | "dashboard"
@@ -77,16 +79,7 @@ function renderView(view: View): React.ReactNode {
     case "items":
       return <ItemForge />;
     case "sound":
-      return (
-        <div className="flex items-center justify-center h-full text-[var(--color-text-dim)]">
-          <div className="text-center">
-            <Volume2 size={64} className="mx-auto mb-4 opacity-30" />
-            <p className="text-lg font-heading">Soundboard</p>
-            <p className="text-sm mt-2">Local audio clips for ambience</p>
-            <p className="text-xs mt-1 opacity-60">Coming soon</p>
-          </div>
-        </div>
-      );
+      return <Soundboard />;
     default:
       return null;
   }
@@ -239,6 +232,9 @@ export default function App() {
           ) : null}
         </main>
       </div>
+
+      {/* Toast notifications */}
+      <ToastContainer />
     </div>
   );
 }