feat: 增强FeedListFeature和MeFeature的首次加载逻辑

- 在FeedListFeature和MeFeature中新增isFirstLoad状态，确保仅在首次加载时请求数据。
- 更新MainView以简化视图切换逻辑，使用isHidden修饰符控制视图显示。
- 新增View+isHidden扩展，提供视图隐藏功能，提升代码可读性和复用性。

yana/Features/MeFeature.swift

@@ -5,6 +5,7 @@ import ComposableArchitecture
 struct MeFeature {
     @Dependency(\.apiService) var apiService
     struct State: Equatable {
+        var isFirstLoad: Bool = true
         var userInfo: UserInfo?
         var isLoadingUserInfo: Bool = false
         var userInfoError: String?
@@ -32,17 +33,9 @@ struct MeFeature {
     func reduce(into state: inout State, action: Action) -> Effect<Action> {
         switch action {
         case .onAppear:
-            guard state.uid > 0 else { return .none }
-            state.isLoadingUserInfo = true
-            state.isLoadingMoments = true
-            state.userInfoError = nil
-            state.momentsError = nil
-            state.page = 1
-            state.hasMore = true
-            return .merge(
-                fetchUserInfo(uid: state.uid),
-                fetchMoments(uid: state.uid, page: 1, pageSize: state.pageSize)
-            )
+            guard state.isFirstLoad else { return .none }
+            state.isFirstLoad = false
+            return .send(.refresh)
         case .refresh:
             guard state.uid > 0 else { return .none }
             state.isRefreshing = true