[Domain] Provide runtime demo FacilityLayout2D

[95x8x9]

Summary

• Add a domain-owned runtime demo FacilityLayout2D generator (DemoLayouts::demoFacility()) that application/domain can call without reading tests/ fixtures.
• Keep layout IDs stable for scenario/event targeting and ensure the demo layout passes ImportValidationService with no blocking issues.

Related Issue

• Closes Task-런타임 데모 FacilityLayout2D 제공 #134

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)

Risks / Follow-up

• Follow-up: wire this runtime demo layout into the Qt application workflow when the run/authoring UI needs a non-import entrypoint.