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/Controls/UnifiedAGVCanvas.cs

@@ -144,10 +144,6 @@ namespace AGVNavigationCore.Controls
         public event EventHandler<(MapNode From, MapNode To)> ConnectionDeleted;
         public event EventHandler MapChanged;
 
-        // AGV 이벤트
-        public event EventHandler<IAGV> AGVSelected;
-        public event EventHandler<IAGV> AGVStateChanged;
-
         #endregion
 
         #region Properties