Feature/delta team/epic r04 (#7)

## Summary

epic r04 - begin refactor

## Change Type

- [x] Cowork feature
- [ ] Bug fix
- [ ] Core AI contribution
- [ ] Test / hardening
- [ ] Performance
- [ ] Documentation

## Related Work

Cowork Task:

Core Repo: http://34.143.229.138/gitea-admin/fsg-ai-core-assets

Core AI Issue:

Core Task:

Related PR:

## Scope

What is intentionally included?

What is intentionally NOT included?

## Validation

- [ ] Unit tests
- [ ] Integration tests
- [ ] Manual verification
- [ ] Regression check

Commands / evidence:

## Security Impact

Permission / credential / network / customer data impact:

## Compatibility

- [ ] No breaking change
- [ ] Breaking change documented

## Reviewer Notes

Anything Cowork reviewers should pay attention to.

---------

Co-authored-by: Anh Tran Nguyen Minh <anhtnm1@fpt.com>
Co-authored-by: Huong Le Thi Thien <huongltt35@fpt.com>
Co-authored-by: Nam Pham Dinh Thanh <nampdt@fpt.com>
Co-authored-by: Vu Dam Tuan <vudt15@fpt.com>
Co-authored-by: Hiep Ha Van <hiephv3@fpt.com>
Co-authored-by: Lam Hoang Van <lamhv7@fpt.com>
Reviewed-on: #7
Co-authored-by: Duy Le Huu <duylh19@fpt.com>

core/routing/store.py

@@ -68,6 +68,11 @@ class AssessmentStore:
         store_path: Optional[Path] = None,
         history_dir: Optional[Path] = None,
     ) -> None:
+        """``store_path`` để None thì dùng file mặc định trong thư mục cấu hình.
+
+        Import ``CONFIG_DIR`` muộn ngay trong thân hàm: nạp nó lúc import module sẽ
+        kéo theo cả cây cấu hình vào mọi test dùng lớp này.
+        """
         if store_path is None:
             from ...config import CONFIG_DIR  # lazy: avoids import cost in tests
             store_path = CONFIG_DIR / _DEFAULT_STORE_NAME
@@ -107,9 +112,11 @@ class AssessmentStore:
         return out
 
     def last_updated(self) -> Optional[str]:
+        """Mốc thời gian lần chấm điểm gần nhất; ``None`` nếu chưa chấm lần nào."""
         return self.load_raw().get("last_updated")
 
     def policy(self) -> str:
+        """Chính sách chấm điểm đã lưu; chưa có thì mặc định 'balanced'."""
         return self.load_raw().get("policy") or Policy.BALANCED.value
 
     # -- write ---------------------------------------------------------- #