Add comprehensive test suite for game mechanics and level handling

- Introduced `test_final_level_flow.py` to validate final level transitions and game end scenarios.
- Created `test_game_over_flow.py` to ensure game over conditions trigger correctly based on rat counts.
- Implemented `test_keybindings.py` to verify keybinding configurations and their context-specific actions.
- Developed `test_level_editor.py` to assess level editor functionalities and layout computations.
- Added `test_level_io.py` for testing level data serialization and deserialization.
- Established `test_loop_logic_parity.py` to ensure consistent game state across multiple simulation runs.
- Created `test_non_regression.py` to simulate game behavior and capture states for future verification.
- Implemented `test_verify.py` to compare current game states against a golden master for regression detection.

tests/test_game_over_flow.py

@@ -0,0 +1,88 @@
+
+import os
+import sys
+import unittest
+import random
+from pathlib import Path
+
+# Add current directory to path
+sys.path.append(os.getcwd())
+
+# Set SDL to use dummy video driver for headless environments
+os.environ["SDL_VIDEODRIVER"] = "dummy"
+os.environ["SDL_AUDIODRIVER"] = "dummy"
+os.environ["MICE_DISABLE_JOYSTICK"] = "1"
+
+from rats import MiceMaze
+from engine.state_machine import GameState
+from engine.sdl2 import GameWindow
+
+def mock_init_audio(self):
+    self.music_enabled = False
+    self.audio_devs = {"base": 0, "effects": 0, "music": 0}
+    self.sound_volume = 0
+    self.music_volume = 0
+
+class TestGameOverFlow(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        GameWindow.show_intro = lambda *args, **kwargs: None
+        GameWindow.show_loading_screen = lambda *args, **kwargs: None
+        GameWindow._init_audio_system = mock_init_audio
+        GameWindow.play_sound = lambda *args, **kwargs: None
+        GameWindow.stop_sound = lambda *args, **kwargs: None
+        
+    def setUp(self):
+        random.seed(42)
+        # Load a standard level
+        self.game = MiceMaze("assets/Rat/level.dat", level_index=0)
+        self.game.game_status = "game"
+        self.game.state_machine.transition_to(GameState.PLAYING)
+        
+    def test_defeat_triggers_game_over_state(self):
+        """Verify that having > 200 rats triggers GAME_OVER state, not PAUSED."""
+        print("\nTesting defeat condition (> 200 rats)...")
+        
+        # Manually inject > 200 rats to trigger defeat
+        from units.rat import Male
+        for i in range(210):
+            self.game.unit_manager.spawn_unit(Male, (1, 1))
+            
+        # Run one update cycle
+        self.game.update_maze()
+        
+        # Check end condition
+        self.assertTrue(self.game.game_end[0], "Game should be marked as ended")
+        self.assertEqual(self.game.game_end[1], "defeat", "End reason should be defeat")
+        
+        # CRITICAL CHECK: State must be GAME_OVER, not PAUSED
+        current_state = self.game.state_machine.current_state
+        print(f"Current State: {current_state}")
+        print(f"Legacy game_status: {self.game.game_status}")
+        
+        self.assertEqual(current_state, GameState.GAME_OVER, 
+                         f"Game should be in GAME_OVER state, but was in {current_state}")
+        
+    def test_victory_triggers_victory_state(self):
+        """Verify that clearing all rats triggers VICTORY state."""
+        print("\nTesting victory condition (0 rats)...")
+        
+        # Clear all units
+        self.game.units.clear()
+        
+        # Run one update cycle
+        self.game.update_maze()
+        
+        # Check end condition
+        self.assertTrue(self.game.game_end[0], "Game should be marked as ended")
+        self.assertEqual(self.game.game_end[1], "level_clear", "End reason should be level_clear")
+        
+        # State must be VICTORY
+        current_state = self.game.state_machine.current_state
+        print(f"Current State: {current_state}")
+        
+        self.assertEqual(current_state, GameState.VICTORY, 
+                         f"Game should be in VICTORY state, but was in {current_state}")
+
+if __name__ == "__main__":
+    unittest.main()