pub fn expand_triggers(
registry: &Registry,
ctx: Option<&Context>,
owner_schema: &str,
event: &str,
) -> Result<Vec<Value>, String>Expand description
展开某 schema + 事件的触发链(只展开一层)。
产出 step 列表;每个 step:
{ "name", "onFields", "when", "command"|"callback" }