fix(be): client contest record authorization

[mnseok]

Description

Endpoint	함수	참가 여부 판단 기준	Record 기반 여부	수정
POST /contest/:id/participation	registerContest()	ContestRecord로 이미 참가했는지 확인	예	UserContest의 role 검증 후 불러오는 방식으로 수정.
GET /contest/:id	getContest()	UserContest로 참가자/운영진 여부 계산	아니오	수정대상 x
DELETE /contest/:id/participation	unregisterContest()	UserContest와 ContestRecord를 함께 삭제	부분적 사용	수정대상 x
GET /contest/:id/leaderboard	getContestLeaderboard()	ContestRecord에서 참가자 점수·순위 조회	아니오. 통계 데이터	수정대상 x
GET /contest/:id/statistics/user/:userId	getContestUserStatistics()	대상자의 ContestRecord 존재 여부 확인	아니오. 실제로 Record를 기반으로 통계 데이터를 만들기 때문에 검증 필요.	수정대상 x

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• [ v] Read the Contributing Guidelines
• [ v] Read the Contributing Guidelines and follow the Commit Convention
• [ v] Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves.
• [ v] Ideally, include relevant tests that fail without this PR but pass with it.

Summary by CodeRabbit

• Bug Fixes

  • Improved contest registration status checks for more accurate participant recognition.
  • Strengthened duplicate-registration validation to prevent incorrect registration results.

• Style

  • Reformatted course Q&A data definitions for improved readability without changing functionality.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 4ea5c531-9c4f-4791-9b0c-d3bbf7631d57

📥 Commits

Reviewing files that changed from the base of the PR and between d123c7f and 03b19b3.

📒 Files selected for processing (2)

• apps/backend/apps/client/src/contest/contest.service.ts
• apps/backend/prisma/schema.prisma

Included review availability: Your plan provides up to 10 included reviews per hour; 9 remain after this review.

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📝 Walkthrough

Walkthrough

Contest registration status and duplicate-registration checks now use participant-role userContest records. The CourseQnA Prisma model declarations were reformatted without schema changes.

Changes

Contest registration

Layer / File(s)	Summary
Participant registration checks apps/backend/apps/client/src/contest/contest.service.ts	getContests and registerContest now check participant-role userContest records instead of contest records.

Schema formatting

Layer / File(s)	Summary
CourseQnA declaration formatting apps/backend/prisma/schema.prisma	The CourseQnA field and relation declarations were reformatted. Their schema semantics remain unchanged.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 03b19

This change updates contest participation authorization behavior and related schema definitions; no actionable merge-blocking risk remains after normal checks and review.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 1…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the backend contest record authorization fix, which matches the main change in the pull request.

Full details: Docstring Coverage

Explanation

No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 1 files. (1 skipped: 1 unsupported.)

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch t2906-client-contest-record-authorization

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