Module registry 

配置注册表

静态注册表，声明每个可配置字段的元信息（类型、默认值、是否支持动态覆盖/热重载）。

Structs

ConfigFieldDef

配置字段定义

Enums

ConfigValueType

配置值类型

Functions

all_fields

Get all field definitions in the registry.

fields_for_service

Get all field definitions for a given service.

get_field

Look up a field definition by its key.