refactor: 백엔드 배포 환경 파일 통합

[cocoyoon]

Summary

• api-server + ai-server 2개 env 파일을 루트 .env.backend.{env} 1개로 통합
• docker-compose 3개 환경(dev/staging/prod) 모두 적용
• deploy-backend.sh env 체크 단순화
• 충돌 키 LOG_FORMAT은 compose environment에서 서비스별 오버라이드 (api=text, ai=json)

Test plan

• docker compose config --services 3개 환경 모두 정상 확인
• Mac Mini에서 bash scripts/deploy-backend.sh prod up --build 실행 검증

Closes #118

🤖 Generated with Claude Code

---

Note

Medium Risk
Medium risk because it changes how dev/staging/prod Docker Compose loads environment variables; misnamed/missing keys or wrong paths could break deployments or alter runtime configuration.

Overview
Introduces a single unified backend env template (.env.backend.example) and switches the Docker stack (dev/staging/prod compose files) to load env from repo-root .env.backend.{env} instead of separate api/ai env files.

Updates deploy-backend.sh and the stack README to use the unified env file, simplifies env-file existence checks, and sets LOG_FORMAT per-service via compose overrides (api=text, ai=json).

^{Reviewed by Cursor Bugbot for commit 6edc54c. Configure here.}

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Project	Deployment	Actions	Updated (UTC)
decoded-app	Ready	Preview, Comment	Apr 8, 2026 5:43am

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Cursor Bugbot has reviewed your changes and found 2 potential issues.

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^{Reviewed by Cursor Bugbot for commit 6edc54c. Configure here.}

[cursor]

Stale env file path in Meilisearch error message

Medium Severity

The MEILISEARCH_MASTER_KEY required-variable error message on line 86 still references the old path packages/api-server/.env.prod, but this PR moved the env file to .env.backend.prod at the repo root. The comment at line 4 of the same file was correctly updated to .env.backend.prod, so this is an inconsistent omission. When MEILISEARCH_MASTER_KEY is missing in prod, the error will direct the operator to a file that no longer exists.

 

^{Reviewed by Cursor Bugbot for commit 6edc54c. Configure here.}

[cursor]

Dev compose missing ENV override for api service

Medium Severity

The dev compose api service environment block doesn't override ENV, unlike staging (ENV: staging) and prod (ENV: production). Previously this was safe because the dev-specific env file had the correct value. Now the unified env file template sets ENV=production, so a dev api container created from a copy of .env.backend.example would run with ENV=production. The Rust config uses ENV to determine behavior like default log format and the reported environment mode.

 

^{Reviewed by Cursor Bugbot for commit 6edc54c. Configure here.}