refactor: 提取 useToast hook + Toast 组件，消除 4 处重复的通知逻辑

将 state + setTimeout 自动消失逻辑封装为 useToast hook，
Toast UI 统一为组件支持 top/bottom 两种位置，净减约 12 行。

src/app/profile/page.tsx

@@ -24,6 +24,8 @@ import {
   Heart,
 } from "lucide-react";
 import EmptyState from "@/components/EmptyState";
+import Toast from "@/components/Toast";
+import { useToast } from "@/hooks/useToast";
 import RestaurantImage from "@/components/RestaurantImage";
 import { ProfileCardSkeleton, RecordItemSkeleton } from "@/components/Skeleton";
 import { getUserId, getCachedProfile, setCachedProfile, setCachedPreferences, logout } from "@/lib/userId";
@@ -68,12 +70,7 @@ export default function ProfilePage() {
 
   const [showHistory, setShowHistory] = useState(true);
   const [showFavorites, setShowFavorites] = useState(true);
-  const [toast, setToast] = useState("");
-
-  const showToast = useCallback((msg: string) => {
-    setToast(msg);
-    setTimeout(() => setToast(""), 2200);
-  }, []);
+  const toast = useToast();
 
   useEffect(() => {
     const cached = getCachedProfile();
@@ -141,7 +138,7 @@ export default function ProfilePage() {
         setProfile((prev) => prev ? { ...prev, username: trimmed } : prev);
         setCachedProfile({ id: userId, username: trimmed, avatar: profile!.avatar });
         setEditingUsername(false);
-        showToast("用户名已更新");
+        toast.show("用户名已更新");
       } else {
         setUsernameMsg(data.error ?? "更新失败");
       }
@@ -180,7 +177,7 @@ export default function ProfilePage() {
         setCurrentPassword("");
         setNewPassword("");
         setConfirmPassword("");
-        showToast("密码已更新");
+        toast.show("密码已更新");
       } else {
         setPasswordMsg(data.error ?? "更新失败");
       }
@@ -202,10 +199,10 @@ export default function ProfilePage() {
         setProfile((prev) => prev ? { ...prev, avatar: emoji } : prev);
         setCachedProfile({ id: userId, username: profile!.username, avatar: emoji });
         setEditingAvatar(false);
-        showToast("头像已更新");
+        toast.show("头像已更新");
       }
     } catch {
-      showToast("更新失败");
+      toast.show("更新失败");
     }
   };
 
@@ -244,9 +241,9 @@ export default function ProfilePage() {
         body: JSON.stringify({ userId, favoriteId: favId }),
       });
       setFavorites((f) => f.filter((x) => x.id !== favId));
-      showToast("已取消收藏");
+      toast.show("已取消收藏");
     } catch {
-      showToast("操作失败");
+      toast.show("操作失败");
     }
   };
 
@@ -714,19 +711,7 @@ export default function ProfilePage() {
         </motion.div>
       </div>
 
-      <AnimatePresence>
-        {toast && (
-          <motion.div
-            className="fixed left-1/2 top-10 z-60 -translate-x-1/2 rounded-xl bg-elevated px-4 py-2.5 text-xs font-medium text-heading shadow-lg ring-1 ring-subtle"
-            initial={{ opacity: 0, y: -12, x: "-50%" }}
-            animate={{ opacity: 1, y: 0, x: "-50%" }}
-            exit={{ opacity: 0, y: -12, x: "-50%" }}
-            transition={{ type: "spring", stiffness: 400, damping: 25 }}
-          >
-            {toast}
-          </motion.div>
-        )}
-      </AnimatePresence>
+      <Toast message={toast.message} />
     </div>
   );
 }