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/working_timer_test.py

@@ -0,0 +1,42 @@
+#!/usr/bin/env python3
+"""Test that timers work correctly with --exec"""
+import mcrfpy
+from mcrfpy import automation
+
+print("Setting up timer test...")
+
+# Create a scene
+mcrfpy.createScene("timer_works")
+mcrfpy.setScene("timer_works")
+ui = mcrfpy.sceneUI("timer_works")
+
+# Add visible content
+frame = mcrfpy.Frame(100, 100, 300, 200,
+                    fill_color=mcrfpy.Color(255, 0, 0),
+                    outline_color=mcrfpy.Color(255, 255, 255),
+                    outline=3.0)
+ui.append(frame)
+
+caption = mcrfpy.Caption(mcrfpy.Vector(150, 150),
+                        text="TIMER TEST SUCCESS",
+                        fill_color=mcrfpy.Color(255, 255, 255))
+caption.size = 24
+ui.append(caption)
+
+# Timer callback with correct signature
+def timer_callback(runtime):
+    print(f"\n✓ Timer fired successfully at runtime: {runtime}")
+    
+    # Take screenshot
+    filename = f"timer_success_{int(runtime)}.png"
+    result = automation.screenshot(filename)
+    print(f"Screenshot saved: {filename} - Result: {result}")
+    
+    # Cancel timer and exit
+    mcrfpy.delTimer("success_timer")
+    print("Exiting...")
+    mcrfpy.exit()
+
+# Set timer
+mcrfpy.setTimer("success_timer", timer_callback, 1000)
+print("Timer set for 1 second. Game loop starting...")