fix(wechat): resolve scheduled task cancel via manage LLM instead of hard rules

Use a lightweight LLM over active task lists to pick taskId for cancel,
exclude page.generate from scheduled-task inbound, and remove single-task
auto-cancel so Cursor page generation stays isolated.

Co-authored-by: Cursor <cursoragent@cursor.com>

server/portal-integration-services-bootstrap.mjs

@@ -33,6 +33,7 @@ export async function bootstrapPortalIntegrationServices({
   taskUnifiedService = null,
   sessionSnapshotService = null,
   wechatScheduleLlmConfigService,
+  wechatScheduledTaskManageLlmConfigService = null,
   wechatIntentRouter = null,
   wechatCursorExecutorPolicyService = null,
   agentRunGateway = null,
@@ -178,6 +179,7 @@ export async function bootstrapPortalIntegrationServices({
           ? taskUnifiedService
           : null,
       wechatScheduleLlmConfigService,
+      wechatScheduledTaskManageLlmConfigService,
       llmProviderService,
       chatIntentRouter,
       wechatIntentRouter,