feat(comment): add campaignDiscussion comment type for campaign discussion board

[yingshinlee]

這是什麼

在寫作活動頁（WritingChallenge）新增「留言區」討論板的後端支援：新增評論類型 campaignDiscussion，沿用 Comment 體系的 targetId / targetTypeId 綁到 campaign（與 moment 類型先例同手法）。

權限模型：公開可讀；只有報名成功者（campaign_user.state = 'succeeded'）與 creator / organizerIds / managerIds 可發言。

前端對應 PR：thematters/matters-web 的同名分支 feat/campaign-discussion。
產品脈絡：七日書活動頁要開一個輕量討論區，重用圍爐眾聊的既有架構。

改動

檔案	內容
src/common/enums/index.ts	COMMENT_TYPE.campaignDiscussion；MAX_CAMPAIGN_COMMENT_LENGTH = 240（比照 moment）
src/types/comment.ts	enum CommentType 加 campaignDiscussion；CommentInput 加 optional campaignId
src/types/campaign.ts	WritingChallenge.discussion / discussionCount
src/mutations/comment/putComment.ts	campaign 分支（target 解析、參加者權限檢查、240 字上限、無單一 target author 時跳過 block 檢查、invalidateFQC 用 NODE_TYPES.Campaign）
src/queries/comment/campaign/discussion.ts（新）	公開讀、無成員檢查，比照 circle/discussion.ts（cursor 分頁、filter）
src/queries/comment/campaign/discussionCount.ts（新）	比照 circle/discussionCount.ts
src/queries/campaign/index.ts	註冊 resolver
src/queries/comment/node.ts	campaignDiscussion → 回傳 WritingChallenge（前端回覆/編輯靠 comment.node 取 campaignId）
src/connectors/campaignService.ts	isParticipant(campaignId, userId) helper

不需要 migration

entity_type 已有 campaign（20240703145306_create_campaign_tables.js），comment 表 targetId/targetTypeId 為通用欄位。

刻意不做（MVP）

• 通知：campaign 留言不觸發任何 notice（circle mention 分支已 guard）。
• 即時推送：無 WebSocket，定位是討論區非聊天室。

權限驗收矩陣

角色	讀	寫
未登入 / 未報名 / pending / rejected	✅	❌
succeeded 參加者、creator/organizers/managers	✅	✅

備註

• enum 追加與 optional 欄位皆向後相容，不影響 article/circle/moment 既有行為。
• Draft 原因：由社群貢獻者提交，尚未在完整 dev 環境跑過測試，請團隊協助 review 與驗證。

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 80.35714% with 22 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.46%. Comparing base (85bdbe1) to head (409a9d5).
⚠️ Report is 19 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/queries/comment/campaign/discussion.ts	48.14%	12 Missing and 2 partials ⚠️
src/mutations/comment/putComment.ts	83.33%	5 Missing and 1 partial ⚠️
...0000_alter_comment_type_add_campaign_discussion.js	80.00%	1 Missing ⚠️
src/mutations/comment/unvoteComment.ts	90.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4841      +/-   ##
===========================================
- Coverage    72.82%   72.46%   -0.36%     
===========================================
  Files         1054     1057       +3     
  Lines        21263    21013     -250     
  Branches      4671     4586      -85     
===========================================
- Hits         15485    15228     -257     
+ Misses        5706     5309     -397     
- Partials        72      476     +404     

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