refactor: streamline routes to RESTful naming conventions

Remove /api/ prefix and consolidate route groups:
- /api/lobby/* -> /games, /snake, /logout (top-level)
- /game/{game_id} + /api/game/{game_id}/* -> /games/{id}/*
- /snake/{game_id} + /api/snake/{game_id}/* -> /snake/{id}/*
- /api/auth/* -> /auth/*
- Standardize snake join page to use return_url= (was return=)

features/lobby/routes.go

@@ -19,12 +19,10 @@ func SetupRoutes(
 ) error {
 	router.Get("/", HandleLobbyPage(queries, sessions, snakeStore))
 
-	router.Route("/api/lobby", func(r chi.Router) {
-		r.Post("/create-game", HandleCreateGame(store, sessions))
-		r.Delete("/game/{id}", HandleDeleteGame(store, sessions))
-		r.Post("/create-snake", HandleCreateSnakeGame(snakeStore, sessions))
-		r.Post("/logout", HandleLogout(sessions))
-	})
+	router.Post("/games", HandleCreateGame(store, sessions))
+	router.Delete("/games/{id}", HandleDeleteGame(store, sessions))
+	router.Post("/snake", HandleCreateSnakeGame(snakeStore, sessions))
+	router.Post("/logout", HandleLogout(sessions))
 
 	return nil
 }