init: RAG 知识库服务初始提交

- 后端 API（Flask + Gunicorn）
- RAG 引擎（混合检索 + 云端 Reranker + 引用溯源）
- 文档解析（MinerU + 多格式支持）
- Docker 生产部署配置
- 排除前端项目、敏感配置、模型文件

core/status_codes.py

@@ -0,0 +1,125 @@
+"""
+状态码定义
+
+统一的业务状态码，用于 API 响应中标识操作结果。
+状态码格式：4位数字，前两位表示类别，后两位表示具体状态
+- 10xx: 处理中
+- 20xx: 成功
+- 40xx: 客户端错误
+- 50xx: 服务端错误
+"""
+
+from typing import Dict
+
+# 状态码到消息的映射
+_STATUS_MESSAGES: Dict[int, str] = {
+    # 处理中状态 (10xx)
+    1000: "处理中",
+    1001: "文件接收中",
+    1002: "文件解析中",
+    1003: "向量化中",
+    1010: "同步进行中",
+    1020: "出题生成中",
+    1021: "批阅进行中",
+
+    # 成功状态 (20xx)
+    2000: "操作成功",
+    2001: "创建成功",
+    2002: "文件上传成功",
+    2003: "批量上传完成",
+    2004: "删除成功",
+    2005: "更新成功",
+    2010: "同步完成",
+    2020: "出题成功",
+    2021: "批阅完成",
+    2030: "图片描述更新成功",
+
+    # 客户端错误 (40xx)
+    4000: "请求参数错误",
+    4001: "未授权",
+    4002: "禁止访问",
+    4003: "资源不存在",
+    4004: "没有上传文件",
+    4005: "没有选择文件",
+    4006: "请指定目标向量库",
+    4007: "不支持的文件格式",
+    4008: "文件大小超过限制",
+    4009: "文档解析失败",
+    4010: "文件不存在",
+    4011: "向量库不存在",
+    4012: "文件内容为空",
+    4013: "权限不足",
+
+    # 服务端错误 (50xx)
+    5000: "服务器内部错误",
+    5001: "服务不可用",
+    5002: "向量化失败",
+    5003: "LLM调用失败",
+    5010: "同步失败",
+    5020: "出题失败",
+    5021: "批阅失败",
+    5030: "图片描述更新失败",
+}
+
+
+def get_status_message(status_code: int) -> str:
+    """
+    根据状态码获取默认消息
+
+    Args:
+        status_code: 业务状态码
+
+    Returns:
+        状态码对应的默认消息
+    """
+    return _STATUS_MESSAGES.get(status_code, "未知状态")
+
+
+# ==================== 常用状态码常量 ====================
+
+# 处理中 (10xx)
+PROCESSING = 1000
+FILE_RECEIVING = 1001
+FILE_PARSING = 1002
+VECTORIZING = 1003
+SYNC_RUNNING = 1010
+EXAM_GENERATING = 1020
+EXAM_GRADING = 1021
+
+# 成功 (20xx)
+SUCCESS = 2000
+CREATED = 2001
+UPLOAD_SUCCESS = 2002
+BATCH_UPLOAD_SUCCESS = 2003
+DELETE_SUCCESS = 2004
+UPDATE_SUCCESS = 2005
+SYNC_SUCCESS = 2010
+EXAM_SUCCESS = 2020
+GRADE_SUCCESS = 2021
+IMAGE_DESC_SUCCESS = 2030
+
+# 客户端错误 (40xx)
+BAD_REQUEST = 4000
+UNAUTHORIZED = 4001
+FORBIDDEN = 4002
+NOT_FOUND = 4003
+NO_FILE = 4004
+NO_FILE_SELECTED = 4005
+NO_COLLECTION = 4006
+UNSUPPORTED_FORMAT = 4007
+FILE_TOO_LARGE = 4008
+PARSE_ERROR = 4009
+FILE_NOT_FOUND = 4010
+COLLECTION_NOT_FOUND = 4011
+NO_CONTENT = 4012
+PERMISSION_DENIED = 4013
+
+# 服务端错误 (50xx)
+INTERNAL_ERROR = 5000
+SERVICE_UNAVAILABLE = 5001
+VECTORIZE_ERROR = 5002
+LLM_ERROR = 5003
+SYNC_ERROR = 5010
+EXAM_ERROR = 5020
+GRADE_ERROR = 5021
+IMAGE_DESC_ERROR = 5030