docs: align consolidated solver workflow

phases/linear-static-3d-euler-beam/step12.md

@@ -11,10 +11,10 @@
 - `/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/io-definitions/linear-static-3d-euler-beam-io.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/io.md`
+- `/docs/linear-static-3d-euler-beam/implementation-plan.md`
 - `/include/fesa/model/model_types.hpp`
 - `/include/fesa/model/domain.hpp`
 - `/src/fesa/model/domain.cpp`
@@ -103,7 +103,7 @@ ctest --test-dir .harness/build -C Debug --output-on-failure
 1. semantic positive/negative tests를 production mapper보다 먼저 작성하고 RED를 확인한다.
 2. 승인 subset에 필요한 최소 mapping/validation만 구현해 GREEN을 만든다.
 3. diagnostic field/order와 Domain non-mutation을 점검하고 전체 VERIFY를 수행한다.
-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 12 section에 실제 RED/GREEN/VERIFY command, exit code,
    핵심 output과 변경 파일을 기록한다.
 5. Step 12를 `completed`로 갱신하고 supported mapping/negative diagnostics를 summary에 기록한다.