refactor: restructure core architecture and responsive system

This commit implements a major architectural refactor to improve modularity, type safety, and maintainability across the codebase.

Key changes include:
- **Responsive System Refactor**: Migrated from a monolithic `useResponsive` hook to a set of specialized, granular hooks (`useBreakpoint`, `useOrientation`, `usePlatform`, etc.) located in `src/presentation/hooks/responsive`. This reduces unnecessary re-renders and improves developer experience.
- **Core Service Restructuring**: Introduced a new directory structure for services, including dedicated folders for `datasources`, `mappers`, and domain-specific types (`message`, `post`).
- **Data Layer Improvements**:
    - Centralized JSON parsing logic in `src/database/core/jsonUtils.ts`.
    - Cleaned up repository implementations by removing redundant local utility functions.
    - Refactored `MessageMapper` to use the new centralized JSON utility.
- **Type System Cleanup**:
    - Decomposed the large `src/types/dto.ts` into a modular `src/types/dto/` directory.
    - Simplified `src/types/index.ts` and introduced backward-compatible aliases for core entities.
- **Utility Consolidation**:
    - Created a centralized `src/utils/formatTime.ts` to replace fragmented date formatting logic across various screens and components.
    - Removed deprecated responsive utility files in favor of the new hook-based system.
- **Service Logic Refinement**: Refactored `ApiClient` and `WebSocketService` to use a centralized `showVerificationModal` service, removing duplicated state management for verification prompts.

src/services/mappers/PostMapper.ts

@@ -0,0 +1,129 @@
+/**
+ * 帖子数据映射器
+ * 负责 Post 模型与 API 响应之间的转换
+ */
+
+import { PostModel, UserModel } from '../models';
+import type { PostDTO } from '../../types/dto';
+
+export class PostMapper {
+  static fromApiResponse(response: PostDTO): PostModel {
+    return {
+      id: String(response.id || ''),
+      authorId: String(response.user_id || ''),
+      author: response.author ? this.mapAuthorFromApi(response.author) : undefined,
+      title: response.title || '',
+      content: response.content || '',
+      images: response.images?.map(img => img.url) || [],
+      likeCount: response.likes_count || 0,
+      commentCount: response.comments_count || 0,
+      shareCount: response.shares_count || 0,
+      viewCount: response.views_count || 0,
+      favoriteCount: response.favorites_count || 0,
+      isLiked: response.is_liked || false,
+      isFavorited: response.is_favorited || false,
+      isTop: response.is_pinned || false,
+      status: (response.status || 'published') as 'published' | 'draft' | 'deleted',
+      channelId: response.channel_id,
+      channel:
+        response.channel && response.channel.id
+          ? { id: String(response.channel.id), name: String(response.channel.name || '') }
+          : undefined,
+      tags: [],
+      createdAt: new Date(response.created_at || Date.now()),
+      // 空字符串/缺省时用 created_at，避免误用 Date.now() 导致全部显示「刚修改」
+      updatedAt: new Date(
+        response.updated_at ||
+          response.created_at ||
+          Date.now()
+      ),
+    };
+  }
+
+  /**
+   * 将 API 响应数组转换为应用模型数组
+   */
+  static fromApiResponseList(responses: PostDTO[]): PostModel[] {
+    return responses.map(r => this.fromApiResponse(r));
+  }
+
+  /**
+   * 将应用模型转换为 API 请求数据
+   */
+  static toApiRequest(model: Partial<PostModel>): Record<string, any> {
+    const request: Record<string, any> = {};
+
+    if (model.title !== undefined) {
+      request.title = model.title;
+    }
+    if (model.content !== undefined) {
+      request.content = model.content;
+    }
+    if (model.images !== undefined) {
+      request.images = model.images;
+    }
+    if (model.channelId !== undefined) {
+      request.channel_id = model.channelId;
+    }
+    if (model.tags !== undefined) {
+      request.tags = model.tags;
+    }
+
+    return request;
+  }
+
+  /**
+   * 创建帖子请求
+   */
+  static createPostRequest(
+    title: string,
+    content: string,
+    images?: string[],
+    channelId?: string
+  ): Record<string, any> {
+    const request: Record<string, any> = {
+      title,
+      content,
+    };
+    if (images && images.length > 0) {
+      request.images = images;
+    }
+    if (channelId) {
+      request.channel_id = channelId;
+    }
+    return request;
+  }
+
+  /**
+   * 更新帖子请求
+   */
+  static updatePostRequest(
+    title?: string,
+    content?: string,
+    images?: string[]
+  ): Record<string, any> {
+    const request: Record<string, any> = {};
+    if (title !== undefined) {
+      request.title = title;
+    }
+    if (content !== undefined) {
+      request.content = content;
+    }
+    if (images !== undefined) {
+      request.images = images;
+    }
+    return request;
+  }
+
+  /**
+   * 映射作者信息
+   */
+  private static mapAuthorFromApi(author: any): UserModel {
+    return {
+      id: String(author.id || ''),
+      username: author.username || '',
+      nickname: author.nickname,
+      avatar: author.avatar,
+    };
+  }
+}