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/application/services/job_executor.py

@@ -61,12 +61,16 @@ def _git_short_rev() -> str | None:
         return None
 
 
-def _summary_text(kind: str, result: BacktestResult | FactorTestReport) -> str | None:
+def _summary_text(kind: str, result) -> str | None:
+    from app.domain.entities.selection import SelectionResult
+
     if kind == "backtest" and isinstance(result, BacktestResult):
         s = result.summary
         return f"总收益 {s.total_return_pct:.2f}% · 年化 {s.annual_return_pct:.2f}% · 回撤 {s.max_drawdown_pct:.2f}%"
     if isinstance(result, FactorTestReport):
         return f"IC {result.ic_mean:.4f} · RankIC {result.rank_ic_mean:.4f} · 样本 {result.sample_days} 日"
+    if kind == "selection" and isinstance(result, SelectionResult):
+        return f"as_of {result.as_of_date} · 选出 {result.statistics.selected} / 评估 {result.statistics.evaluated}"
     return None
 
 
@@ -91,10 +95,20 @@ def _execute_inner(
         job_repo.update(job)
         session.commit()
         try:
-            spec = ResearchSpec.model_validate_json(job.spec_json)
-            service = ResearchService(
-                stock_repo_factory(session), daily_repo_factory(session), engine
-            )
+            is_selection = job.kind == "selection"
+            if is_selection:
+                from app.application.services.selection_service import SelectionService
+                from app.domain.entities.selection import SelectionQuery
+
+                spec = SelectionQuery.model_validate_json(job.spec_json)
+                service = SelectionService(
+                    stock_repo_factory(session), daily_repo_factory(session)
+                )
+            else:
+                spec = ResearchSpec.model_validate_json(job.spec_json)
+                service = ResearchService(
+                    stock_repo_factory(session), daily_repo_factory(session), engine
+                )
 
             def _set_stage(name: str) -> None:
                 """阶段上报（v3 §23）：独立短会话写 job.stage 并 commit（子进程同样走 DB）。"""
@@ -108,7 +122,10 @@ def _execute_inner(
                 except Exception:  # noqa: BLE001 —— 阶段上报失败不阻断执行
                     pass
 
-            if spec.type == "backtest":
+            if is_selection:
+                _set_stage("selection")
+                result = service.select(spec)
+            elif spec.type == "backtest":
                 result = service.run_backtest(spec, on_stage=_set_stage)
             else:
                 result = service.run_factor_test(spec, on_stage=_set_stage)
@@ -116,10 +133,10 @@ def _execute_inner(
             result_json = json.dumps(result.model_dump(mode="json"), ensure_ascii=False)
             experiment = ExperimentRecord(
                 id=new_id("EXP"),
-                kind=spec.type,
+                kind=job.kind,
                 spec_json=job.spec_json,
                 result_json=result_json,
-                summary_text=_summary_text(spec.type, result),
+                summary_text=_summary_text(job.kind, result),
                 code_version=_git_short_rev(),
                 job_id=job.id,
                 created_at=datetime.now(),