feat(backend): 更新核心模块和文件处理

- 更新配置模块 (config.py)
- 更新数据库连接 (database.py)
- 更新主应用入口 (main.py)
- 更新数据模型 (models.py)
- 更新基础 Schema (base.py)
- 更新文件处理器 (docx, excel, pdf)
- 更新 Dockerfile

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/core/config.py

@@ -4,7 +4,7 @@ Application Configuration
 
 from functools import lru_cache
 from pydantic_settings import BaseSettings
-from pydantic import Field
+from pydantic import Field, field_validator
 
 
 class Settings(BaseSettings):
@@ -15,12 +15,16 @@ class Settings(BaseSettings):
     DEBUG: bool = True
     HOST: str = "0.0.0.0"
     PORT: int = 8000
+    ALLOWED_ORIGINS: str = Field(
+        default="*",
+        description="Comma-separated list of allowed CORS origins"
+    )
 
     # Database - 使用 SQLite 进行开发/测试
     # 生产环境可切换为 PostgreSQL
     DATABASE_URL: str = Field(
-        default="sqlite:///./ygdataset.db",
-        description="Database connection URL (sqlite:// or postgresql+asyncpg://)"
+        default="sqlite+aiosqlite:///./ygdataset.db",
+        description="Database connection URL (sqlite+aiosqlite:// or postgresql+asyncpg://)"
     )
     DATABASE_URL_SYNC: str = Field(
         default="sqlite:///./ygdataset.db",
@@ -38,8 +42,31 @@ class Settings(BaseSettings):
     DEFAULT_MODEL_PROVIDER: str = "openai"
     DEFAULT_MODEL_NAME: str = "gpt-4o-mini"
 
+    # Security
+    SECRET_KEY: str = Field(
+        default="your-secret-key-change-in-production",
+        description="Secret key for JWT and other security operations"
+    )
+    API_KEY_HEADER: str = "X-API-Key"
+
+    # Pagination
+    DEFAULT_PAGE_SIZE: int = 20
+    MAX_PAGE_SIZE: int = 100
+
+    # Logging
+    LOG_LEVEL: str = "INFO"
+
+    @field_validator("MAX_FILE_SIZE")
+    @classmethod
+    def validate_max_file_size(cls, v: int) -> int:
+        """Validate max file size (max 500MB)"""
+        if v > 500 * 1024 * 1024:
+            return 500 * 1024 * 1024
+        return v
+
     class Config:
         env_file = ".env"
+        env_file_encoding = "utf-8"
         extra = "allow"
 
 
@@ -47,3 +74,7 @@ class Settings(BaseSettings):
 def get_settings() -> Settings:
     """Get cached settings"""
     return Settings()
+
+
+# Create global settings instance
+settings = get_settings()