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.env.example

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+API_KEY=
+MODEL_NAME=gpt-4.1
+DMXAPI_URL=https://www.dmxapi.cn/v1/responses
+JWT_SECRET_KEY=please_change_me
+JWT_ALGORITHM=HS256
+ACCESS_TOKEN_EXPIRE_MINUTES=720
+ADMIN_USERNAME=admin
+ADMIN_PASSWORD=admin123
+DATABASE_URL=sqlite:///./backend/problem_bank.db
+UPLOAD_DIR=./backend/uploads