fix(700줄분리): 진입 파일에서 분리 전 이름 전부 재노출

laptop-sub 가 쓴 AST 대조법(분리 전 커밋의 모듈 정의 이름 ↔ 지금 모듈 `dir()`)을
내 4개에도 적용해 누락 26개를 찾아 되살림.

- `B03_FileInput_Router.py` 누락 17 → 0 (헬퍼 13 + 청크 엔드포인트 4)
- `B03_FileInput_Router_Temp.py` 누락 5 → 0 (`_total_chunks` + 청크 엔드포인트 4)
- `B07_DesignDetail_Router_Support.py` 누락 3 → 0 (`_BASIN_MAX_DISTANCE_M` ·
  `_clip_segment` · `_geometry_lines`)
- `config/config_system.py` 누락 1 → 0 (`_SCS_SOIL` — `import *` 가 밑줄 이름을 안 실음)

검증: 네 파일 모두 **정의 이름 누락 0**(28·19·36·246개 대조), 라우트 수 유지
(B03 7 · temp 9+attach 1 · B07 7), ruff check 통과, tmp/tests 378 passed

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

B07_DesignDetail/B07_DesignDetail_Router_Support.py

@@ -36,6 +36,9 @@ from B07_DesignDetail.B07_DesignDetail_Engine_Cad_Table import (
     QUANTITY_VALUE_KEYS,
 )
 from B07_DesignDetail.B07_DesignDetail_Engine_Template import add_title_fields
+from B07_DesignDetail.B07_DesignDetail_Router_Support_Basin import (
+    _BASIN_MAX_DISTANCE_M as _BASIN_MAX_DISTANCE_M,
+)
 
 # 유역도 배경·파일 입출력 조각은 700줄 제한으로 떼어냈다(2026-09-04).
 # 여기서 그대로 다시 내보내 호출부(`B07_DesignDetail_Router.py`)의 import 경로는 불변이다.
@@ -48,12 +51,18 @@ from B07_DesignDetail.B07_DesignDetail_Router_Support_Basin import (
 from B07_DesignDetail.B07_DesignDetail_Router_Support_Basin import (
     _basins_crs as _basins_crs,
 )
+from B07_DesignDetail.B07_DesignDetail_Router_Support_Basin import (
+    _clip_segment as _clip_segment,
+)
 from B07_DesignDetail.B07_DesignDetail_Router_Support_Basin import (
     _geojson_features as _geojson_features,
 )
 from B07_DesignDetail.B07_DesignDetail_Router_Support_Basin import (
     _geojson_payload as _geojson_payload,
 )
+from B07_DesignDetail.B07_DesignDetail_Router_Support_Basin import (
+    _geometry_lines as _geometry_lines,
+)
 from B07_DesignDetail.B07_DesignDetail_Router_Support_Basin import (
     _too_far_from_route as _too_far_from_route,
 )