Add comments explaining why env vars are used instead of Config

AppHarness._initialize_app calls get_config(reload=True), which
resets any direct Config mutations made before the harness starts.

Author: tartansandal

tests/integration/tests_playwright/test_frontend_path.py

@@ -81,6 +81,8 @@ def onload_redirect_with_prefix_app_dev(tmp_path) -> Generator[AppHarness, None,
     Yields:
         running AppHarness instance
     """
+    # Set via env var rather than Config directly because AppHarness._initialize_app
+    # calls get_config(reload=True), which resets any prior Config mutations.
     os.environ["REFLEX_FRONTEND_PATH"] = "/prefix"
     try:
         with AppHarness.create(

tests/integration/tests_playwright/test_link_hover.py

@@ -28,6 +28,8 @@ def index():
 
 @pytest.fixture
 def link_app(tmp_path_factory) -> Generator[AppHarness, None, None]:
+    # Set via env var rather than Config directly because AppHarness._initialize_app
+    # calls get_config(reload=True), which resets any prior Config mutations.
     os.environ["REFLEX_SHOW_BUILT_WITH_REFLEX"] = "false"
     try:
         with AppHarness.create(