refactor: ECR-002 拆分 runtime 包并加深 analyze 契约（已审）

将 web/services/runtime.py 拆为 runtime/ 子模块并保持门面兼容；补齐 ESS 文档、门面/契约/TF_DF 测试与 CODE_REVIEW Approve。

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

docs/HANDOFF/ECR-002-engineer-to-reviewer.md

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+# HANDOFF — ECR-002 engineer → reviewer
+
+**From:** ENGINEER  
+**To:** REVIEWER  
+**Date:** 2026-08-06  
+**ECR:** ECR-002  
+
+## Ask
+
+对照 ECR-002 Acceptance 做代码审阅；确认 strategies/config 无 diff；golden + 新契约测试通过。
+
+## Artifacts
+
+- `docs/ECR/ECR-002-runtime-split.md`
+- `docs/IMPLEMENTATION_REPORT/ECR-002.md`
+- `docs/TEST_REPORT/ECR-002.md`
+- `docs/ENGINEERING_SPEC/ECR-002-runtime-split.md`
+
+## Diff focus
+
+- `web/services/runtime/`（新包）
+- 删除原 `web/services/runtime.py`
+- `web/tests/test_*.py`、`tests/test_tf_df_init.py`
+- ESS docs 更新
+
+## Out of scope this round
+
+- `chart_tv.js` 拆分
+- 主站 WebSocket
+- strategies/config