[Application] polish layout review approval controls

[SilverSupplier]

Summary

• Layout Review의 승인 가능 상태를 blocking issue 수와 함께 명확히 표시합니다.
• Undo 버튼과 Ctrl+Z 상태를 같은 흐름으로 노출해 승인 전 검토/수정 루프를 안정화합니다.
• Scenario Authoring으로 넘어가기 전 승인 UX를 Sprint 1 demo flow에 맞게 정리합니다.

Related Issue

• Refs Task-도면 import와 구조 검토 application workflow 구현 #117
• Part of EPIC-2 Sprint 1 Demo Vertical Slice #2

Area

• Engine
• Domain
• Application
• Docs
• Build
• Analysis
• Chore

Architecture Check

• I kept the dependency direction application -> domain -> engine.
• I did not add Qt UI code to src/domain.
• I did not add domain or application dependencies to src/engine.
• I used src/ as the include root.

Verification

• cmake --preset windows-debug
• cmake --build --preset build-debug
• ctest --preset test-debug
• cmake --build --preset build-no-app-debug
• ctest --preset test-no-app-debug
• Not run (reason below)

Verification was run on the integrated Sprint 1 stack after splitting this PR.

Risks / Follow-up

• This PR intentionally stays within src/application/ and does not change import/domain validation behavior.
• This is the first PR in a stacked series; following PRs build on this branch for authoring/run/result flow and docs sync.