fix: change logging level to debug for plugin restoration and add tests for warning filters

tests/test_startup_warnings.py

@@ -0,0 +1,17 @@
+import warnings
+
+import app
+
+
+def test_app_installs_known_oss2_invalid_escape_warning_filter():
+    """
+    app 初始化过滤器应覆盖 oss2 在 Python 3.12 下产生的无害转义警告。
+    """
+    app._filter_third_party_startup_warnings()
+    action, message, category, module, lineno = warnings.filters[0]
+
+    assert action == "ignore"
+    assert message.match("invalid escape sequence '\\&'")
+    assert category is SyntaxWarning
+    assert module is None
+    assert lineno == 0