Add /holes/_sfw endpoint to filter NSFW tagged posts

[Copilot]

Adds endpoint to retrieve safe-for-work posts by excluding holes with NSFW tags.

Changes

• Route: GET /api/holes/_sfw returns holes without NSFW tags
• Query: Uses LEFT JOIN on hole_tags with subquery for NSFW tag IDs, filtering on NULL matches
• Test: Verifies NSFW tagged holes are excluded, leverages Tag's BeforeCreate hook (tags starting with * auto-set nsfw=true)

Implementation

// Exclude holes with NSFW tags using optimized LEFT JOIN
nsfwTagIDs := DB.Table("tag").Select("id").Where("nsfw = ?", true)
querySet = querySet.
    Joins("LEFT JOIN hole_tags ON hole.id = hole_tags.hole_id AND hole_tags.tag_id IN (?)", nsfwTagIDs).
    Where("hole_tags.hole_id IS NULL").
    Group("hole.id")

Pattern mirrors ListGoodHoles endpoint. LEFT JOIN approach scales better than NOT IN subquery for large datasets.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Feature Request] 增加一个新接口，获取safe for work的帖子</issue_title>
<issue_description>你的功能需求和某个bug有关吗？
[否]

你想要什么样的功能？
Get /divisions/:id/holes/_sfw
实现上，可能要join tag表，找出nsfw的tag然后处理

</issue_description>

<agent_instructions>Keep modifications minimal.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes [Feature Request] 增加一个新接口，获取safe for work的帖子 #177

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[Copilot]

Pull request overview

This PR adds a new endpoint /api/holes/_sfw that returns holes without NSFW tags, enabling users to filter out not-safe-for-work content. The implementation follows established patterns in the codebase, particularly mirroring the ListGoodHoles endpoint structure.

Key Changes

• New GET endpoint at /holes/_sfw with query parameter support for pagination and ordering
• SQL query uses LEFT JOIN with subquery to efficiently filter out holes with NSFW tags
• Test coverage validates that NSFW-tagged holes are properly excluded

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
apis/hole/routes.go	Registers the new /holes/_sfw route endpoint
apis/hole/apis.go	Implements ListSfwHoles handler with LEFT JOIN query to exclude NSFW-tagged holes
tests/hole_test.go	Adds test case that creates NSFW and safe holes, verifies NSFW filtering works correctly

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