Security: Deleted content exposure + revision history IDOR via sequential IDs

先从受影响的两个端点的 AnswerService.Get 和 GetObjectTimelineDetail 入手，然后将它们的访问检查与 SearchList、GetRevisionList 和 GetQuestion 进行比较。跟踪已删除和待处理的问题、答案及修订是如何加载的。完成标准是：未经身份验证的用户不再能看到已删除的答案，经过身份验证的用户不再能看到已删除或待处理修订的内容，同时获准访问的内容仍然可以访问。

Summary

Two information disclosure issues allow access to deleted/pending content:

1. Deleted Answer Content via GET /answer/api/v1/answer/info (Low-Medium)

`AnswerService.Get()` calls `answerRepo.GetByID()` which fetches answers by raw ID with no `status != deleted` filter. Deleted answers are returned with full content to unauthenticated callers.

Secure comparison: `SearchList` correctly filters: `session.Where("status != ?", entity.AnswerStatusDeleted)`

2. Revision History IDOR via GET /answer/api/v1/activity/timeline/detail (Medium)

`GetObjectTimelineDetail` fetches revision content by sequential integer ID (`autoincr BIGINT`). No check for whether the associated question/answer is deleted or pending. Any authenticated user can enumerate `revision_id=1,2,3...` to read full content of deleted/pending questions and answers.

Secure comparison: `GetRevisionList` correctly checks `objInfo.IsDeleted()` before showing history. `GetQuestion` blocks access to deleted/pending content.

Impact

• Bypasses content moderation (admin-deleted content remains accessible)
• Reveals pending-review content before publication
• Sequential revision IDs make enumeration trivial

Discovery

Found through automated security research comparing content visibility controls across endpoints.