fix(device-sim): 修复设备模拟模块数据库表未创建问题

- 在 models/__init__.py 中导入 EnvConfig, DeviceSimulator, ReportLog 模型
- 确保 SQLAlchemy Base.metadata 注册设备模拟相关表
- 解决新增环境配置后列表显示暂无数据的问题
Co-Authored-By: Claude <noreply@anthropic.com>

backend/app/models/__init__.py

@@ -15,6 +15,7 @@ from app.models.case_result import CaseResult
 from app.models.case_dependency import CaseDependency
 from app.models.security_config import SecurityConfig
 from app.models.vulnerability_result import VulnerabilityResult
+from app.models.device_sim import EnvConfig, DeviceSimulator, ReportLog
 
 __all__ = [
     "Module",
@@ -24,4 +25,7 @@ __all__ = [
     "CaseDependency",
     "SecurityConfig",
     "VulnerabilityResult",
+    "EnvConfig",
+    "DeviceSimulator",
+    "ReportLog",
 ]
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