refactor: 缠论引擎包化与 Web 分层（ECR-001）

将根目录引擎迁入 chanlun/ 并保留兼容 shim；拆分 TF_DF 与 web 服务；
前端模块化；strategies 改用 chanlun 导入；补充 ESS 文档与 golden 回归。

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

docs/HANDOFF/ECR-001-engineer-to-reviewer.md

@@ -0,0 +1,25 @@
+# Handoff
+
+**From:** ENGINEER  
+**To:** REVIEWER  
+**ECR:** ECR-001  
+**State:** coding → review  
+**Date:** 2026-08-05  
+
+## Artifacts
+
+- [x] ECR (Approved / Done pending review)
+- [x] PRODUCT_SPEC / ENGINEERING_SPEC / ADR / RISK N/A
+- [x] IMPLEMENTATION_REPORT
+- [x] TEST_REPORT
+- [ ] CODE_REVIEW
+
+## Goal for receiver
+
+对照 ECR-001 Acceptance 做代码审阅；确认 strategies/config 无 diff；golden 与路由契约通过。
+
+## References
+
+- `docs/IMPLEMENTATION_REPORT/ECR-001.md`
+- `docs/TEST_REPORT/ECR-001.md`
+- `docs/CHANGELOG/CHANGELOG.md`