feat(delegate-task): ⚙️ make sync subagent timeout configurable via syncPollTimeoutMs

Allow users to set `background_task.syncPollTimeoutMs` in config to override
the default 10-minute sync subagent timeout. Affects sync task, sync continuation,
and unstable agent task paths. Minimum value: 60000ms (1 minute).

Co-authored-by: Wine Fox <fox@ling.plus>

src/tools/delegate-task/sync-continuation.ts

@@ -18,7 +18,7 @@ export async function executeSyncContinuation(
   executorCtx: ExecutorContext,
   deps: SyncContinuationDeps = syncContinuationDeps
 ): Promise<string> {
-  const { client } = executorCtx
+  const { client, syncPollTimeoutMs } = executorCtx
   const toastManager = getTaskToastManager()
   const taskId = `resume_sync_${args.session_id!.slice(0, 8)}`
   const startTime = new Date()
@@ -112,7 +112,7 @@ export async function executeSyncContinuation(
         toastManager,
         taskId,
         anchorMessageCount,
-      })
+      }, syncPollTimeoutMs)
       if (pollError) {
         return pollError
       }