feat(api): Add CLI flag and env var to enable test hooks

tests/test_hooks.py

@@ -0,0 +1,24 @@
+import os
+import sys
+sys.path.insert(0, os.path.dirname(os.path.dirname(__file__)))
+import pytest
+from unittest.mock import patch
+import gui
+
+def test_hooks_enabled_via_cli():
+    with patch.object(sys, 'argv', ['gui.py', '--enable-test-hooks']):
+        app = gui.App()
+        assert app.test_hooks_enabled is True
+
+def test_hooks_disabled_by_default():
+    with patch.object(sys, 'argv', ['gui.py']):
+        if 'SLOP_TEST_HOOKS' in os.environ:
+            del os.environ['SLOP_TEST_HOOKS']
+        app = gui.App()
+        assert getattr(app, 'test_hooks_enabled', False) is False
+
+def test_hooks_enabled_via_env():
+    with patch.object(sys, 'argv', ['gui.py']):
+        with patch.dict(os.environ, {'SLOP_TEST_HOOKS': '1'}):
+            app = gui.App()
+            assert app.test_hooks_enabled is True