[Domain] Add two-floor evacuation demo map

[SilverSupplier]

Summary

• Add a built-in Two-floor Evacuation Demo project that opens directly into the run workspace.
• Define a two-floor evacuation layout with U-shaped stair transitions, 2F training/briefing rooms, 1F lobby/vestibules, and east/west exits.
• Add demo fixture coverage for the two-floor baseline/alternative scenarios and regression coverage for stair descent completion.

Related Issue

• Closes [Domain] 2층 데모 맵 정의 추가 #164

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)

Additional checks run:

• cmake --build --preset build-no-app-debug
• ctest --preset test-no-app-debug
• git diff --check

Not run reason:

• Configure was not rerun; verification reused the existing Windows debug preset build tree.

Risks / Follow-up

• The PR includes the app wiring needed to select the built-in two-floor demo from Project Navigator, in addition to the domain fixture scope in [Domain] 2층 데모 맵 정의 추가 #164.
• Future UI polish can make the U-shaped stair visual easier to distinguish in the canvas, but the current regression test verifies the crowd completes after stair descent.