[Docs] domain part 대본 업데이트

[95x8x9]

Summary

• 도메인 계층 대본 add

Related Issue

• None (docs/policy-only PR)

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
• Not run (reason below)
• Docs 수정이므로 test를 진행하지 않음

Risks / Follow-up

• None