feat: Phase 4 — Experiment 自动归档 + 异步 Job（状态机 / SSE / 一键复跑）

- 数据表：job / experiment（spec/result JSON 存档、code_version），Alembic 迁移 53113c80257f
- Job：queued→running→(success|failed) 状态机，BackgroundTasks 本地执行 + 失败兜底标记；结果与 Experiment 关联
- Experiment：每次研究成功自动归档（含 git commit 与收益摘要），支持一键复跑（同 spec 重建 Job）
- API：POST /api/jobs、GET /api/jobs/{id}（内嵌结果）、SSE /api/jobs/{id}/events、/api/experiments 列表/详情/rerun
- 前端：新增「实验」页（列表 / 详情 / 复跑 + Job 轮询）；导航更新
- 端到端验证：真实 20 股 job 提交→后台执行→success→EXP 归档（-12.41%）；executor 成功/失败路径单测
- 测试 73 passed（新增 5 项 Job/Experiment）/ ruff clean / 前端 tsc + build 通过

backend/app/infrastructure/persistence/migrations/versions/53113c80257f_phase4_jobs_and_experiments.py

@@ -0,0 +1,65 @@
+"""phase4 jobs and experiments
+
+Revision ID: 53113c80257f
+Revises: e4d188250fb2
+Create Date: 2026-09-06 17:16:05.976236
+
+"""
+
+from __future__ import annotations
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "53113c80257f"
+down_revision: str | None = "e4d188250fb2"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table(
+        "experiment",
+        sa.Column("id", sa.String(length=32), nullable=False),
+        sa.Column("kind", sa.String(length=16), nullable=False),
+        sa.Column("spec_json", sa.Text(), nullable=False),
+        sa.Column("result_json", sa.Text(), nullable=False),
+        sa.Column("summary_text", sa.String(length=200), nullable=True),
+        sa.Column("code_version", sa.String(length=40), nullable=True),
+        sa.Column("data_version", sa.String(length=40), nullable=True),
+        sa.Column("job_id", sa.String(length=32), nullable=True),
+        sa.Column("created_at", sa.DateTime(), nullable=False),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    op.create_table(
+        "job",
+        sa.Column("id", sa.String(length=32), nullable=False),
+        sa.Column("kind", sa.String(length=16), nullable=False),
+        sa.Column("status", sa.String(length=12), nullable=False),
+        sa.Column("stage", sa.String(length=24), nullable=True),
+        sa.Column("spec_json", sa.Text(), nullable=False),
+        sa.Column("error", sa.Text(), nullable=True),
+        sa.Column("result_json", sa.Text(), nullable=True),
+        sa.Column("experiment_id", sa.String(length=32), nullable=True),
+        sa.Column("created_at", sa.DateTime(), nullable=False),
+        sa.Column("started_at", sa.DateTime(), nullable=True),
+        sa.Column("finished_at", sa.DateTime(), nullable=True),
+        sa.PrimaryKeyConstraint("id"),
+    )
+    with op.batch_alter_table("job", schema=None) as batch_op:
+        batch_op.create_index(batch_op.f("ix_job_status"), ["status"], unique=False)
+
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table("job", schema=None) as batch_op:
+        batch_op.drop_index(batch_op.f("ix_job_status"))
+
+    op.drop_table("job")
+    op.drop_table("experiment")
+    # ### end Alembic commands ###