refactor(router): centralize app route transitions

src/app/auth/components/auth-panel.tsx

@@ -2,9 +2,8 @@
 /**
  * 认证面板：顶层 switch（Facebook / Email）+ 悬浮返回按钮
  */
-import { useRouter } from "next/navigation";
-
 import { BackButton } from "@/app/_components";
+import { useAppNavigator } from "@/router/use-app-navigator";
 import { useAuthDispatch, useAuthState } from "@/stores/auth/auth-context";
 
 import { AuthEmailPanel } from "./auth-email-panel";
@@ -14,7 +13,7 @@ import styles from "./auth-panel.module.css";
 export function AuthPanel() {
   const state = useAuthState();
   const dispatch = useAuthDispatch();
-  const router = useRouter();
+  const navigator = useAppNavigator();
 
   const switchToFacebook = () =>
     dispatch({ type: "AuthPanelModeChanged", mode: "facebook" });
@@ -25,7 +24,7 @@ export function AuthPanel() {
     if (state.authPanelMode === "email") {
       switchToFacebook();
     } else {
-      router.back();
+      navigator.back();
     }
   };