feat(test): 添加dotenv支持并重构测试配置

在.gitignore中添加.env文件
添加dotenv依赖管理环境变量
重构测试用例使用环境变量代替硬编码URL
在playwright配置中加载dotenv并设置baseURL

test/package-lock.json

@@ -9,7 +9,8 @@
       "version": "1.0.0",
       "license": "ISC",
       "dependencies": {
-        "@playwright/test": "1.51.1"
+        "@playwright/test": "^1.51.1",
+        "dotenv": "^16.5.0"
       }
     },
     "node_modules/@playwright/test": {
@@ -27,6 +28,18 @@
         "node": ">=18"
       }
     },
+    "node_modules/dotenv": {
+      "version": "16.5.0",
+      "resolved": "https://registry.npmmirror.com/dotenv/-/dotenv-16.5.0.tgz",
+      "integrity": "sha512-m/C+AwOAr9/W1UOIZUo232ejMNnJAJtYQjUbHoNTBNTJSvqzzDh7vnrei3o3r3m9blf6ZoDkvcw0VmozNRFJxg==",
+      "license": "BSD-2-Clause",
+      "engines": {
+        "node": ">=12"
+      },
+      "funding": {
+        "url": "https://dotenvx.com"
+      }
+    },
     "node_modules/fsevents": {
       "version": "2.3.2",
       "resolved": "https://registry.npmmirror.com/fsevents/-/fsevents-2.3.2.tgz",