feat(job): D2 全市场选股 Job 化（kind=selection 异步）

- Job kind=selection：executor 分支用 SelectionService（spec=SelectionQuery），结果
  落 result_json、自动归档 Experiment（summary：as_of + 选出 N）；/api/jobs 与
  /api/experiments 的 result 解码支持 SelectionResult
- POST /api/selections/jobs：提交 SelectionQuery 为异步 Job（BackgroundTasks/subprocess）
- Web 选股页新增「异步（全市场）」按钮：提交 Job → waitJob 轮询结果（解决同步 60s+）
- tests/test_selection_job.py：executor 执行归档（SelectionResult/Experiment kind）、
  API 提交→轮询→结果与实验列表；全量 pytest + tsc 通过

backend/app/api/selections.py

@@ -9,18 +9,20 @@ GET  /api/selections          历史选股元数据（可过滤 as_of/method）
 
 from __future__ import annotations
 
-from datetime import date
+from datetime import date, datetime
 from typing import Annotated
 
-from fastapi import APIRouter, HTTPException, Query
+from fastapi import APIRouter, BackgroundTasks, HTTPException, Query
 from pydantic import BaseModel
 
 from app.api.deps import (
     DbSession,
+    JobRepoDep,
     SelectionRepoDep,
     SelectionServiceDep,
 )
-from app.application.services.job_executor import new_id
+from app.application.services.job_executor import new_id, run_job_background
+from app.domain.entities.research import JobRecord, JobStatus
 from app.domain.entities.selection import SelectionMeta, SelectionQuery, SelectionResult
 
 router = APIRouter(prefix="/selections", tags=["selections"])
@@ -31,6 +33,26 @@ class SelectionRun(BaseModel):
     result: SelectionResult
 
 
+@router.post("/jobs", summary="提交全市场/长任务选股为异步 Job")
+def submit_selection_job(
+    query: SelectionQuery,
+    background: BackgroundTasks,
+    session: DbSession,
+    job_repo: JobRepoDep,
+) -> dict:
+    job = JobRecord(
+        id=new_id("JOB"),
+        kind="selection",
+        spec_json=query.model_dump_json(),
+        status=JobStatus.QUEUED,
+        created_at=datetime.now(),
+    )
+    job_repo.create(job)
+    session.commit()
+    background.add_task(run_job_background, job.id)
+    return {"job_id": job.id, "status": job.status}
+
+
 @router.post("", response_model=SelectionRun, summary="执行一次选股（同步）并落库")
 def run_selection(
     query: SelectionQuery,