fix: reset UserContext on login/logout to prevent admin page stuck on re-login

Root cause: UserContext.checked was never reset on logout, causing AdminLayout's use_effect to skip get_current_user() on subsequent mounts, leaving the page in (checked=true, user=None) limbo.

- Reset ctx.user and ctx.checked on logout in admin_layout.rs
- Reset ctx.checked on login success in login.rs so AdminLayout re-validates session on mount

src/components/admin_layout.rs

@@ -17,7 +17,6 @@ pub fn AdminLayout() -> Element {
     let route = use_route::<Route>();
     let show_skeleton = use_delayed_loading(move || !(ctx.checked)());
 
-    // 只在首次挂载时加载用户数据
     use_effect(move || {
         if !(ctx.checked)() {
             (ctx.checked).set(true);
@@ -69,6 +68,8 @@ pub fn AdminLayout() -> Element {
                 onclick: move |_| {
                     spawn(async move {
                         let _ = logout().await;
+                        ctx.user.set(None);
+                        ctx.checked.set(false);
                         let _ = navigator.push(Route::Login {});
                     });
                 },

src/pages/login.rs

@@ -3,6 +3,7 @@ use dioxus::router::components::Link;
 
 use crate::api::auth::{login, AuthResponse};
 use crate::components::forms::{AlertBox, FormInput, FormLabel, BUTTON_PRIMARY_CLASS};
+use crate::context::UserContext;
 use crate::router::Route;
 
 #[component]
@@ -10,6 +11,7 @@ pub fn Login() -> Element {
     let mut username = use_signal(|| "".to_string());
     let mut password = use_signal(|| "".to_string());
     let mut error = use_signal(|| None::<String>);
+    let mut ctx: UserContext = use_context();
 
     let on_submit = Callback::new(move |_| {
         error.set(None);
@@ -24,6 +26,7 @@ pub fn Login() -> Element {
                     token: Some(_token),
                     ..
                 }) => {
+                    ctx.checked.set(false);
                     let _ = dioxus::router::navigator().push(Route::Admin {});
                 }
                 Ok(AuthResponse {