feat(post): enhance post handling with channel integration

- Updated PostHandler to include channel information in post responses.
- Introduced PostChannelBrief DTO to represent channel details associated with posts.
- Modified post conversion functions to support channel data, ensuring proper mapping of channel IDs to channel names.
- Enhanced ChannelRepository and ChannelService to facilitate batch retrieval of channels by IDs.
- Updated wire generation to inject channel service into post handler for improved functionality.

internal/repository/channel_repo.go

@@ -48,6 +48,19 @@ func (r *ChannelRepository) GetByID(id string) (*model.Channel, error) {
 	return &channel, nil
 }
 
+// ListByIDs 按 ID 列表查询频道（用于帖子列表批量填充 channel 名称）
+func (r *ChannelRepository) ListByIDs(ids []string) ([]*model.Channel, error) {
+	if len(ids) == 0 {
+		return nil, nil
+	}
+	var list []*model.Channel
+	err := r.db.Where("id IN ?", ids).Find(&list).Error
+	if err != nil {
+		return nil, err
+	}
+	return list, nil
+}
+
 func (r *ChannelRepository) Delete(id string) error {
 	return r.db.Delete(&model.Channel{}, "id = ?", id).Error
 }