MinIO設定をCoolify対応に整備し、bucket自動作成を追加

compose:
- MinIOにヘルスチェック(mc ready)を追加し、api/workerはhealthyを待つように変更
- 全認証情報を${VAR:-default}でパラメータ化し、Coolifyの環境変数/シークレットで上書き可能に
- MINIO_SERVER_URL / MINIO_BROWSER_REDIRECT_URL でリバースプロキシ背後の公開URLに対応
- workerの依存先をapiからpostgres+minioに修正し、起動順序のデッドロックを解消

API:
- S3StorageにensureBucket()を追加(HeadBucket→なければCreateBucket、冪等)
- runtime起動時にbucketを自動作成し、minio-init依存を必須ではなくした

.env.exampleにMinIO関連変数を追記

.env.example

@@ -2,18 +2,24 @@ NODE_ENV=development
 PORT=4000
 PUBLIC_BASE_URL=http://localhost:4000
 WEB_ORIGIN=http://localhost:3000
-NEXT_PUBLIC_API_BASE_URL=http://localhost:4000
 NEXT_PUBLIC_AUTH_MODE=demo
 
-# Use PostgreSQL + MinIO in Docker Compose. Leave DATABASE_URL empty for memory mode.
+# --- Storage (MinIO via docker compose) -------------------------------------
+# Leave DATABASE_URL empty to run with an in-memory store instead of Postgres.
 DATABASE_URL=postgres://altdock:altdock@localhost:5432/altdock
 STORAGE_MODE=s3
 S3_ENDPOINT=http://localhost:9000
 S3_REGION=us-east-1
 S3_BUCKET=altdock
 S3_ACCESS_KEY_ID=minioadmin
-S3_SECRET_ACCESS_KEY=minioadmin
+S3_SECRET_ACCESS_KEY=minioadmin123
 S3_FORCE_PATH_STYLE=true
+# MinIO root credentials, consumed by docker-compose.yml. CHANGE in production.
+MINIO_ROOT_USER=minioadmin
+MINIO_ROOT_PASSWORD=minioadmin123
+# Only needed when MinIO is behind a reverse proxy / domain (e.g. on Coolify):
+MINIO_SERVER_URL=
+MINIO_BROWSER_REDIRECT_URL=
 
 # demo works without an identity provider; production should use generic OIDC.
 AUTH_MODE=demo