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/plugin/tool-registry.ts

@@ -67,6 +67,7 @@ export function createToolRegistry(args: {
     disabledSkills: skillContext.disabledSkills,
     availableCategories,
     availableSkills: skillContext.availableSkills,
+    syncPollTimeoutMs: pluginConfig.background_task?.syncPollTimeoutMs,
     onSyncSessionCreated: async (event) => {
       log("[index] onSyncSessionCreated callback", {
         sessionID: event.sessionID,