feat(engine): implement perspective FOV, pathfinding, and GUI text widgets

Major Engine Enhancements:
- Complete FOV (Field of View) system with perspective rendering
  - UIGrid.perspective property for entity-based visibility
  - Three-layer overlay colors (unexplored, explored, visible)
  - Per-entity visibility state tracking
  - Perfect knowledge updates only for explored areas

- Advanced Pathfinding Integration
  - A* pathfinding implementation in UIGrid
  - Entity.path_to() method for direct pathfinding
  - Dijkstra maps for multi-target pathfinding
  - Path caching for performance optimization

- GUI Text Input Widgets
  - TextInputWidget class with cursor, selection, scrolling
  - Improved widget with proper text rendering and input handling
  - Example showcase of multiple text input fields
  - Foundation for in-game console and chat systems

- Performance & Architecture Improvements
  - PyTexture copy operations optimized
  - GameEngine update cycle refined
  - UIEntity property handling enhanced
  - UITestScene modernized

Test Suite:
- Interactive visibility demos showing FOV in action
- Pathfinding comparison (A* vs Dijkstra)
- Debug utilities for visibility and empty path handling
- Sizzle reel demo combining pathfinding and vision
- Multiple text input test scenarios

This commit brings McRogueFace closer to a complete roguelike engine
with essential features like line-of-sight, intelligent pathfinding,
and interactive text input capabilities.

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

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

tests/dijkstra_interactive.py

@@ -17,10 +17,10 @@ The path between selected entities is automatically highlighted.
 import mcrfpy
 import sys
 
-# Colors
+# Colors - using more distinct values
 WALL_COLOR = mcrfpy.Color(60, 30, 30)
-FLOOR_COLOR = mcrfpy.Color(200, 200, 220)
-PATH_COLOR = mcrfpy.Color(200, 250, 220)
+FLOOR_COLOR = mcrfpy.Color(100, 100, 120)  # Darker floor for better contrast
+PATH_COLOR = mcrfpy.Color(50, 255, 50)     # Bright green for path
 ENTITY_COLORS = [
     mcrfpy.Color(255, 100, 100),  # Entity 1 - Red
     mcrfpy.Color(100, 255, 100),  # Entity 2 - Green