chore: Rename project from WebTriviasMulti to Trivy

- Update all code references to new name
- Rename design document
- Update package.json
- Update frontend titles and branding

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/main.py

@@ -21,15 +21,15 @@ sio = socketio.AsyncServer(
 @asynccontextmanager
 async def lifespan(app: FastAPI):
     # Startup
-    print("Starting WebTriviasMulti server...")
+    print("Starting Trivy server...")
     yield
     # Shutdown
-    print("Shutting down WebTriviasMulti server...")
+    print("Shutting down Trivy server...")
 
 
 # FastAPI app
 app = FastAPI(
-    title="WebTriviasMulti API",
+    title="Trivy API",
     description="API para el juego de trivia multiplayer",
     version="1.0.0",
     lifespan=lifespan
@@ -59,7 +59,7 @@ socket_app = socketio.ASGIApp(sio, app)
 @app.get("/")
 async def root():
     return {
-        "message": "WebTriviasMulti API",
+        "message": "Trivy API",
         "version": "1.0.0",
         "status": "running"
     }