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/trace_interactive.py

@@ -0,0 +1,23 @@
+#!/usr/bin/env python3
+"""Trace interactive mode by monkey-patching"""
+import sys
+import mcrfpy
+
+# Monkey-patch to detect interactive mode
+original_ps1 = None
+if hasattr(sys, 'ps1'):
+    original_ps1 = sys.ps1
+    
+class PS1Detector:
+    def __repr__(self):
+        import traceback
+        print("\n!!! sys.ps1 accessed! Stack trace:")
+        traceback.print_stack()
+        return ">>> "
+        
+# Set our detector
+sys.ps1 = PS1Detector()
+
+print("Trace script loaded, ps1 detector installed")
+
+# Do nothing else - let the game run