feat(navigation): add profile stack navigator and fix API endpoints

- Add ProfileStackNavigatorComponent with full navigation stack (Profile, Settings, EditProfile, AccountSecurity, MyPosts, Bookmarks, NotificationSettings, BlockedUsers)
- Add null checks for response data in authService login, register, and refreshToken methods
- Fix postService API routes to use correct endpoints (/posts instead of /posts/cursor)
- Remove completed cursor pagination design document

src/services/postService.ts

@@ -287,19 +287,17 @@ class PostService {
 
   /**
    * 获取帖子列表（游标分页）
-   * GET /api/v1/posts/cursor
+   * GET /api/v1/posts
    * @param params 游标分页请求参数（包含 post_type 可选：recommend, follow, hot, latest）
    */
-  async getPostsCursor(
-    params: CursorPaginationRequest = {}
-  ): Promise<CursorPaginationResponse<Post>> {
-    try {
-      const response = await api.get<CursorPaginationResponse<Post>>('/posts/cursor', {
-        params: {
-          cursor: params.cursor,
-          page_size: params.page_size,
-          post_type: params.post_type,
-        },
+   async getPostsCursor(
+     params: CursorPaginationRequest = {}
+   ): Promise<CursorPaginationResponse<Post>> {
+     try {
+       const response = await api.get<CursorPaginationResponse<Post>>('/posts', {
+        cursor: params.cursor,
+        page_size: params.page_size,
+        post_type: params.post_type,
       });
       return response.data;
     } catch (error) {
@@ -315,7 +313,7 @@ class PostService {
 
   /**
    * 搜索帖子（游标分页）
-   * GET /api/v1/posts/search/cursor
+   * GET /api/v1/posts/search
    * @param query 搜索关键词
    * @param params 游标分页请求参数
    */
@@ -324,11 +322,9 @@ class PostService {
     params: CursorPaginationRequest = {}
   ): Promise<CursorPaginationResponse<Post>> {
     try {
-      const response = await api.get<CursorPaginationResponse<Post>>('/posts/search/cursor', {
-        params: {
-          ...params,
-          keyword: query,
-        },
+      const response = await api.get<CursorPaginationResponse<Post>>('/posts/search', {
+        ...params,
+        keyword: query,
       });
       return response.data;
     } catch (error) {
@@ -344,7 +340,7 @@ class PostService {
 
   /**
    * 获取用户帖子列表（游标分页）
-   * GET /api/v1/users/:id/posts/cursor
+   * GET /api/v1/users/:id/posts
    * @param userId 用户ID
    * @param params 游标分页请求参数
    */
@@ -354,8 +350,8 @@ class PostService {
   ): Promise<CursorPaginationResponse<Post>> {
     try {
       const response = await api.get<CursorPaginationResponse<Post>>(
-        `/users/${userId}/posts/cursor`,
-        { params }
+        `/users/${userId}/posts`,
+        params
       );
       return response.data;
     } catch (error) {