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).

packages/context/workspace-context/src/index.ts

@@ -212,9 +212,7 @@ export function apply(ctx: Context, config: Config): void {
   }
 
   ctx.on('agent/pre-step', async (
-    agent: Agent,
-    messages,
-    { step, signal },
+    { agent, messages, step, signal },
     next,
   ): Promise<PreStepDecision> => {
     const decision = await next()