Fix --exec interactive prompt bug and create comprehensive test suite

Major fixes:
- Fixed --exec entering Python REPL instead of game loop
- Resolved screenshot transparency issue (requires timer callbacks)
- Added debug output to trace Python initialization

Test suite created:
- 13 comprehensive tests covering all Python-exposed methods
- Tests use timer callback pattern for proper game loop interaction
- Discovered multiple critical bugs and missing features

Critical bugs found:
- Grid class segfaults on instantiation (blocks all Grid functionality)
- Issue #78 confirmed: Middle mouse click sends 'C' keyboard event
- Entity property setters have argument parsing errors
- Sprite texture setter returns improper error
- keypressScene() segfaults on non-callable arguments

Documentation updates:
- Updated CLAUDE.md with testing guidelines and TDD practices
- Created test reports documenting all findings
- Updated ROADMAP.md with test results and new priorities

The Grid segfault is now the highest priority as it blocks all Grid-based functionality.

tests/ui_Grid_test_no_grid.py

@@ -0,0 +1,28 @@
+#!/usr/bin/env python3
+"""Test setup without Grid creation"""
+import mcrfpy
+
+print("Starting test...")
+
+# Create test scene
+print("[DEBUG] Creating scene...")
+mcrfpy.createScene("grid_test")
+print("[DEBUG] Setting scene...")
+mcrfpy.setScene("grid_test")
+print("[DEBUG] Getting UI...")
+ui = mcrfpy.sceneUI("grid_test")
+print("[DEBUG] UI retrieved")
+
+# Test texture creation
+print("[DEBUG] Creating texture...")
+texture = mcrfpy.Texture("assets/kenney_ice.png", 16, 16)
+print("[DEBUG] Texture created")
+
+# Test vector creation
+print("[DEBUG] Creating vectors...")
+pos = mcrfpy.Vector(10, 10)
+size = mcrfpy.Vector(400, 300)
+print("[DEBUG] Vectors created")
+
+print("All setup complete, Grid creation would happen here")
+print("PASS")