refactor(agent): unify agent-scoped event signatures as payload objects

All agent/* and agent-loop/config-start-failed events take one payload
object carrying the agent subject; waterfall/serial payloads require a
signal and keep next as the final argument. PreStepContext and
RequestFailureContext are unfolded into payloads and retired.
goal/changed follows the same shape so agentEvents keeps its listener
error containment. ReactLoopAgent builds its scope carrier once in the
constructor. Regenerates scope resolvers, tool-cordis api catalog, and
docs catalogs; updates all affected listeners, tests, and the
core-data-structures docs (en + zh).

docs/core-data-structures/core.zh.md

@@ -615,19 +615,7 @@ pre-step 决策使用与持久 user-role 输入相同、带标识的 `UserMessag
 
 源码：[`packages/core/agent/src/types.ts`](../../packages/core/agent/src/types.ts)
 
-`agent/pre-step` 接收独占的已领取批次，以及拟进入步骤的坐标与取消 signal。首次提案在已打开的轮次内、任何步骤开始前运行；工具 continuation 可以在步骤之间提交空的已领取批次：
-
-```ts type-equiv
-/** Coordinates and cancellation for a proposed step. */
-interface PreStepContext {
-  /** Turn that will own the step. */
-  readonly turn: number
-  /** Step proposed by the loop. */
-  readonly step: number
-  /** Current turn cancellation signal. */
-  readonly signal: AbortSignal
-}
-```
+`agent/pre-step` 接收一个 payload，携带独占的已领取批次（`messages`）、拟进入步骤的坐标（`turn`、`step`）与当前轮次的取消 `signal`。首次提案在已打开的轮次内、任何步骤开始前运行；工具 continuation 可以在步骤之间提交空的已领取批次：
 
 它返回 `PreStepDecision`。reject 不会打开步骤。enter 提供在 `step/start` 后追加的完整消息批次；最终决策省略的已领取消息保持已删除，而领取后插入的输入仍留待后续处理：