refactor: Remove unused functions and fields from pathfinding and models

Removed from AGVPathfinder.cs:
- ConvertToDetailedPath() - unused private method
- CalculatePathDistance() - unused private method
- ValidatePath() - unused public method
- ValidatePhysicalConstraints() - only called by ValidatePath (now removed)
- OptimizePath() - unused public method (TODO placeholder only)
- GetPathSummary() - unused public method (debug helper)

Kept essential methods:
- FindNearestJunction() - used by FindPath_test
- FindNearestJunctionOnPath() - used by FindPath_test
- MakeDetailData() - used by FindPath_test
- MakeMagnetDirection() - used by FindPath_test

Removed from VirtualAGV.cs:
- _targetId field - never used
- _currentId field - never used
- _rotationSpeed field - never used (read-only, no references)

Removed from UnifiedAGVCanvas.cs:
- AGVSelected event - unused
- AGVStateChanged event - unused

Result: Cleaner codebase, reduced technical debt, easier maintenance

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Cs_HMI/AGVLogic/AGVNavigationCore/Models/VirtualAGV.cs

@@ -50,8 +50,6 @@ namespace AGVNavigationCore.Models
         private string _agvId;
         private Point _currentPosition;
         private Point _prevPosition;
-        private string _targetId;
-        private string _currentId;
         private AgvDirection _currentDirection;
         private AgvDirection _prevDirection;
         private AGVState _currentState;
@@ -75,7 +73,6 @@ namespace AGVNavigationCore.Models
 
         // 시뮬레이션 설정
         private readonly float _moveSpeed = 50.0f;     // 픽셀/초
-        private readonly float _rotationSpeed = 90.0f; // 도/초
         private bool _isMoving;
 
         #endregion