docs: remove retired workflow instructions and repair references

phases/nonlinear-static-newton-raphson/step6.md

@@ -1,12 +1,15 @@
 # Step 6: backend-neutral-tangent-solver
 
+> 과거 개발 계획이다. 아래 작업·상태·예시는 현재 실행 지시가 아니다.
+> 현재 구현과 검증 한계는 [기능 요약](../../docs/nonlinear-static-newton-raphson/README.md)을 따른다.
+
 ## 읽어야 할 파일
 
 - `AGENTS.md`
-- `docs/ARCHITECTURE.md`
-- `docs/ADR.md`
-- `docs/nonlinear-static-newton-raphson/formulation.md`
-- `docs/nonlinear-static-newton-raphson/numerical-review.md`
+- `../../docs/solver-core/README.md`
+- `../../docs/solver-core/README.md`
+- `../../docs/nonlinear-static-newton-raphson/formulation.md`
+- `../../docs/nonlinear-static-newton-raphson/README.md`
 - `include/fesa/solvers/linear/linear_solver.h`
 - `include/fesa/solvers/linear/mkl_pardiso_solver.h`
 - `src/fesa/solvers/linear/mkl_pardiso_solver.cpp`
@@ -88,7 +91,7 @@ ctest --preset windows-msvc-ninja-debug --show-only=json-v1
 ctest --preset windows-msvc-ninja-debug --output-on-failure
 ```
 
-Use the ignored `.harness/config.json` preset contract. The Harness process must inherit VsDevCmd x64 and `FESA_GTEST_SOURCE_DIR`, `MKL_DIR`, `TBB_DIR`, and `HDF5_DIR` from its parent launch environment.
+Use the ignored 과거 검증 자료(정리됨) preset contract. The Harness process must inherit VsDevCmd x64 and `FESA_GTEST_SOURCE_DIR`, `MKL_DIR`, `TBB_DIR`, and `HDF5_DIR` from its parent launch environment.
 
 ## 상태 기록