fix: Playwright API camelCase → snake_case (Python 版)

- getByPlaceholder → get_by_placeholder
- getByRole → get_by_role
- getByText → get_by_text
- getByTestId → get_by_test_id

tests/web/test_login/test_login.py

@@ -64,15 +64,15 @@ class TestLoginPageDirect:
         """验证登录页可直接访问并正常渲染。"""
         page.goto(f"{web_config['base_url']}/login")
         # 登录页应存在用户名输入框
-        assert page.getByPlaceholder("请输入用户名").is_visible()
+        assert page.get_by_placeholder("请输入用户名").is_visible()
 
     @pytest.mark.p1
     def test_login_page_elements(self, page: Page, web_config):
         """验证登录页所有关键元素存在。"""
         page.goto(f"{web_config['base_url']}/login")
-        assert page.getByPlaceholder("请输入用户名").is_visible()
-        assert page.getByPlaceholder("请输入密码").is_visible()
-        assert page.getByRole("button", name="登录").is_visible()
+        assert page.get_by_placeholder("请输入用户名").is_visible()
+        assert page.get_by_placeholder("请输入密码").is_visible()
+        assert page.get_by_role("button", name="登录").is_visible()
 
     @pytest.mark.p1
     def test_double_login_session_redirect(self, page: Page, web_config, ensure_login):