Refactor widget tests for H5 line generation and validation

- Simplified tests for H5 line creation, focusing on single line generation with a numeric 16-digit label.
- Updated assertions to validate the generated H5 line's label and URI structure.
- Removed redundant tests related to default H5 line URLs and local access, consolidating functionality into fewer tests.
- Added new tests to ensure correct URL generation from configured fallback order and query parameter handling.
- Enhanced test coverage for restoring cached H5 line URLs and validating their structure.

README.md

@@ -1,17 +1,11 @@
 # im_webview_app
 
-Flutter WebView 套壳 App，启动后会请求 `/client_config/query` 获取 H5 线路配置，并加载第一条可用线路。
+Flutter WebView 套壳 App。启动时只会生成并加载一个 H5 URL；如果当前 URL 探测或加载失败，壳层会重新生成下一个 URL 并替换当前 WebView，项目运行过程中始终只持有一个 H5 URL。
 
-默认情况下，非本地 Web 访问会使用当前服务地址的 origin 作为 H5 线路和接口域名，例如访问 `https://app.example.com/app/` 时会请求 `https://app.example.com/client_config/query`。本地访问（如 `localhost`、`127.0.0.1`）继续使用固定兜底域名 `https://h5-test.imharry.work/`。
+默认 URL 来自代码中的泛域名模板，会生成 16 位数字子域名，并通过查询参数把 Flutter 壳请求地址传给 H5：
 
-## H5 线路切换
-
-线路切换在 Flutter 套壳层完成。远程配置不可用时，会先使用启动兜底线路；也可以在打包时覆盖启动线路或配置接口地址：
-
-```bash
-flutter build apk --release --dart-define=H5_LINE_URLS=https://h5-one.example/,https://h5-two.example/
-flutter build apk --release --dart-define=CLIENT_CONFIG_QUERY_URL=https://api.example.com/client_config/query
-flutter build apk --release --dart-define=BOOTSTRAP_H5_LINE_URL=https://h5-one.example/
+```text
+https://1234567890123456.albzyuxq.vip/?flutter_shell=1&flutter_shell_url=https%3A%2F%2F1234567890123456.albzyuxq.vip
 ```
 
 ## 本地打包