fix: safely dedupe linked pipeline jobs

[ystyleb]

Summary

• keep the most progressed pipeline job when duplicate front-10 auto-execution jobs exist for the same range
• reuse active range jobs in the auto-execution runtime instead of starting another duplicate job
• only hide linked pipeline tasks in the task center while the wrapping workflow task is still acting as the primary task

Testing

• node --test tests/novelDirectorAutoExecution.test.js tests/novelDirectorAutoExecutionRuntime.test.js tests/novelWorkflowTaskAdapter.test.js tests/novelPipelineDedup.test.js tests/taskCenterVisibility.test.js

Notes

• pnpm --filter @ai-novel/server build still reports unrelated existing type errors on current upstream/main, but the updated dist files for these touched modules were emitted and the targeted tests above passed.

[wnagchi]

已按 review 建议修正后合并：复用同区间已有活跃 pipeline job 时，服务层现在会先显式恢复该 job，再返回复用结果，不再只挂回一个数据库里仍是 queued / running 但当前进程未继续调度的冷任务。这样自动导演接回已有前 10 章流水线时，不会再因为绕过底层调度逻辑而卡住；对应回归测试也已补上。