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/simple_interactive_visibility.py

@@ -0,0 +1,46 @@
+#!/usr/bin/env python3
+"""Simple interactive visibility test"""
+
+import mcrfpy
+import sys
+
+# Create scene and grid
+print("Creating scene...")
+mcrfpy.createScene("vis_test")
+
+print("Creating grid...")
+grid = mcrfpy.Grid(grid_x=10, grid_y=10)
+
+# Initialize grid
+print("Initializing grid...")
+for y in range(10):
+    for x in range(10):
+        cell = grid.at(x, y)
+        cell.walkable = True
+        cell.transparent = True
+        cell.color = mcrfpy.Color(100, 100, 120)
+
+# Create entity
+print("Creating entity...")
+entity = mcrfpy.Entity(5, 5, grid=grid)
+entity.sprite_index = 64
+
+print("Updating visibility...")
+entity.update_visibility()
+
+# Set up UI
+print("Setting up UI...")
+ui = mcrfpy.sceneUI("vis_test")
+ui.append(grid)
+grid.position = (50, 50)
+grid.size = (300, 300)
+
+# Test perspective
+print("Testing perspective...")
+grid.perspective = -1  # Omniscient
+print(f"Perspective set to: {grid.perspective}")
+
+print("Setting scene...")
+mcrfpy.setScene("vis_test")
+
+print("Ready!")