fix(agents): handle overloaded failover separately (#38301)

* fix(agents): skip auth-profile failure on overload

* fix(agents): note overload auth-profile fallback fix

* fix(agents): classify overloaded failures separately

* fix(agents): back off before overload failover

* fix(agents): tighten overload probe and backoff state

* fix(agents): persist overloaded cooldown across runs

* fix(agents): tighten overloaded status handling

* test(agents): add overload regression coverage

* fix(agents): restore runner imports after rebase

* test(agents): add overload fallback integration coverage

* fix(agents): harden overloaded failover abort handling

* test(agents): tighten overload classifier coverage

* test(agents): cover all-overloaded fallback exhaustion

* fix(cron): retry overloaded fallback summaries

* fix(cron): treat HTTP 529 as overloaded retry

src/test-utils/model-fallback.mock.ts

@@ -4,7 +4,7 @@ export async function runWithModelFallback(params: {
   run: (
     provider: string,
     model: string,
-    options?: { allowRateLimitCooldownProbe?: boolean },
+    options?: { allowTransientCooldownProbe?: boolean },
   ) => Promise<unknown>;
 }) {
   return {