fix(compaction): resolve retry before goal continuation return

Active-goal threshold compaction can pre-empt the normal post-turn tail
and return once it schedules a deferred handoff or auto-continue. When
that turn is the successful response from an auto-retry, returning there
skips the later retry-gate cleanup and leaves isRetrying stuck.

Resolve the completed retry gate before the compaction-continuation
return, and cover the retry-success-over-threshold path so future
changes cannot strand prompt()/waitForIdle() behind a stale retry state.

Refs #3174

packages/coding-agent/src/session/agent-session.ts

@@ -2855,6 +2855,7 @@ export class AgentSession {
 						deferredHandoff: compactionResult.deferredHandoff,
 						continuationScheduled: compactionResult.continuationScheduled,
 					});
+					this.#resolveRetry();
 					await emitAgentEndNotification();
 					return;
 				}