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/force_non_interactive.py

@@ -0,0 +1,29 @@
+#!/usr/bin/env python3
+"""Force Python to be non-interactive"""
+import sys
+import os
+
+print("Attempting to force non-interactive mode...")
+
+# Remove ps1/ps2 if they exist
+if hasattr(sys, 'ps1'):
+    delattr(sys, 'ps1')
+if hasattr(sys, 'ps2'):
+    delattr(sys, 'ps2')
+
+# Set environment variable
+os.environ['PYTHONSTARTUP'] = ''
+
+# Try to set stdin to non-interactive
+try:
+    import fcntl
+    import termios
+    # Make stdin non-interactive by removing ICANON flag
+    attrs = termios.tcgetattr(0)
+    attrs[3] = attrs[3] & ~termios.ICANON
+    termios.tcsetattr(0, termios.TCSANOW, attrs)
+    print("Modified terminal attributes")
+except:
+    print("Could not modify terminal attributes")
+
+print("Script complete")