feat: 添加应用管理和生成签名链接功能

- 新增 platform_apps 表和 App 模型
- 新增应用管理页面 /apps
- 应用配置页面添加"生成链接"功能
- 支持一键生成带签名的访问 URL

backend/app/main.py

@@ -7,6 +7,7 @@ from .routers import stats_router, logs_router, config_router, health_router
 from .routers.auth import router as auth_router
 from .routers.tenants import router as tenants_router
 from .routers.tenant_apps import router as tenant_apps_router
+from .routers.apps import router as apps_router
 
 settings = get_settings()
 
@@ -30,6 +31,7 @@ app.include_router(health_router)
 app.include_router(auth_router, prefix="/api")
 app.include_router(tenants_router, prefix="/api")
 app.include_router(tenant_apps_router, prefix="/api")
+app.include_router(apps_router, prefix="/api")
 app.include_router(stats_router, prefix="/api")
 app.include_router(logs_router, prefix="/api")
 app.include_router(config_router, prefix="/api")