feat: 添加 H5 线路切换功能；支持动态加载和切换不同线路的 URL

test/widget_test.dart

@@ -30,6 +30,26 @@ void main() {
         isFalse);
   });
 
+  test('exposes configured H5 URLs as Flutter shell lines', () {
+    final lines = AppConfig.h5Lines;
+
+    expect(lines, isNotEmpty);
+    expect(lines.first.label, '线路1');
+    expect(lines.first.url, AppConfig.homeUrl(lineIndex: 0));
+    expect(Uri.parse(lines.first.url).host, 'h5-test.imharry.work');
+  });
+
+  test('falls back to the first H5 line for invalid line indexes', () {
+    expect(AppConfig.homeUrl(lineIndex: -1), AppConfig.h5Lines.first.url);
+    expect(AppConfig.homeUrl(lineIndex: 99), AppConfig.h5Lines.first.url);
+  });
+
+  test('matches runtime URLs back to their Flutter shell line', () {
+    final lineUrl = AppConfig.h5Lines.first.url;
+
+    expect(AppConfig.lineIndexForUrl('${lineUrl}login'), 0);
+  });
+
   test('refreshes an H5 route URL without adding branding to the URL', () {
     final uri = Uri.parse(
       AppConfig.withFreshShellParams(
@@ -48,6 +68,22 @@ void main() {
         isFalse);
   });
 
+  test('keeps independent non-legacy H5 hosts when removing shell params', () {
+    final uri = Uri.parse(
+      AppConfig.canonicalizeMainFrameUrl(
+        'https://line-two.example/login?shell_app_name=Old'
+        '&flutter_shell=1#shell_app_logo=old',
+      ),
+    );
+
+    expect(uri.host, 'line-two.example');
+    expect(uri.path, '/login');
+    expect(uri.queryParameters.containsKey('shell_app_name'), isFalse);
+    expect(uri.queryParameters.containsKey('flutter_shell'), isFalse);
+    expect(Uri.splitQueryString(uri.fragment).containsKey('shell_app_logo'),
+        isFalse);
+  });
+
   test('rewrites legacy H5 host main-frame URLs to the canonical host', () {
     final uri = Uri.parse(
       AppConfig.canonicalizeMainFrameUrl(