[Domain] Reroute agents when exits are blocked

[95x8x9]

Summary

• Switches exit selection to a weighted shortest-path (nearest reachable exit) instead of BFS hops.
• Replans full exit routes when the next planned doorway/connection becomes blocked.
• Adds per-agent replanning cooldowns to prevent per-frame pathfinding spikes when no exit is available.

Related Issue

• Closes Task-차단된 출구 재탐색 및 재계획 쿨다운(성능 개선) #160

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

• Cooldown values may need tuning based on larger scenarios; follow-up can add a scenario-level config if needed.