docs: align consolidated solver workflow

phases/linear-static-3d-euler-beam/step19.md

@@ -11,9 +11,9 @@
 - `/AGENTS.md`
 - `/docs/ARCHITECTURE.md`
 - `/docs/ADR.md`
-- `/docs/requirements/linear-static-3d-euler-beam.md`
-- `/docs/formulations/3d-isoparametric-euler-beam-formulation.md`
-- `/docs/implementation-plans/linear-static-3d-euler-beam.md`
+- `/docs/linear-static-3d-euler-beam/requirements.md`
+- `/docs/linear-static-3d-euler-beam/formulation.md`
+- `/docs/linear-static-3d-euler-beam/implementation-plan.md`
 - `/include/fesa/math/vector.hpp`
 - `/include/fesa/math/sparse_matrix.hpp`
 - `/include/fesa/fem/dof_manager.hpp`
@@ -86,7 +86,7 @@ ctest --test-dir .harness/build -C Debug --output-on-failure
 1. partition/mapping tests를 먼저 추가하고 RED를 확인한다.
 2. elimination에 필요한 최소 block extraction으로 GREEN을 만든다.
 3. nonzero `dc`와 전체 VERIFY를 확인한다.
-4. `/docs/implementation-plans/linear-static-3d-euler-beam-implementation-report.md`의
+4. `/docs/linear-static-3d-euler-beam/implementation-report.md`의
    Step 19 section에 실제 RED/GREEN/VERIFY command, exit code,
    핵심 output과 변경 파일을 기록한다.
 5. Step 19를 `completed`로 갱신하고 partition/reconstruction evidence를 summary에 기록한다.