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.

src/main.cpp

@@ -165,14 +165,21 @@ int run_python_interpreter(const McRogueFaceConfig& config, int argc, char* argv
         delete engine;
         return result;
     }
-    else if (config.interactive_mode || config.python_mode) {
-        // Interactive Python interpreter
+    else if (config.interactive_mode) {
+        // Interactive Python interpreter (only if explicitly requested with -i)
         Py_InspectFlag = 1;
         PyRun_InteractiveLoop(stdin, "<stdin>");
         Py_Finalize();
         delete engine;
         return 0;
     }
+    else if (!config.exec_scripts.empty()) {
+        // With --exec, run the game engine after scripts execute
+        engine->run();
+        Py_Finalize();
+        delete engine;
+        return 0;
+    }
     
     delete engine;
     return 0;