Render startup immediately and defer native work with a smooth home transition

mobile/test/school/lazy_school_session_test.dart

@@ -0,0 +1,58 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:webview_flutter_platform_interface/webview_flutter_platform_interface.dart';
+import 'package:hepan_everyday/features/school/school_session.dart';
+import 'package:hepan_everyday/domain/school_term.dart';
+
+import '../support/fake_school_web.dart';
+
+class CountingSchoolPlatform extends FakeSchoolPlatform {
+  int creations = 0;
+  @override
+  PlatformWebViewController createPlatformWebViewController(
+    PlatformWebViewControllerCreationParams params,
+  ) {
+    creations++;
+    return super.createPlatformWebViewController(params);
+  }
+}
+
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+  test('local timetable startup does not construct the school browser', () {
+    final platform = CountingSchoolPlatform();
+    WebViewPlatform.instance = platform;
+    final session = SchoolSession();
+    try {
+      expect(platform.creations, 0);
+      expect(session.connectionState, SchoolConnectionState.signedOut);
+      expect(session.hasOpened, isFalse);
+    } finally {
+      session.dispose();
+    }
+  });
+  test(
+    'opening school creates one reusable browser with navigation policy',
+    () async {
+      final platform = CountingSchoolPlatform();
+      WebViewPlatform.instance = platform;
+      final session = SchoolSession();
+      try {
+        await session.openTimetable(term: SchoolTerm(73));
+        expect(platform.creations, 1);
+        final controller = session.web;
+        expect(session.web, same(controller));
+        expect(platform.creations, 1);
+        expect(platform.web.loads, isNotEmpty);
+        final decision = await platform.delegate.navigation(
+          NavigationRequest(
+            url: 'https://unrelated.example/',
+            isMainFrame: true,
+          ),
+        );
+        expect(decision, NavigationDecision.prevent);
+      } finally {
+        session.dispose();
+      }
+    },
+  );
+}

mobile/test/school/term_selection_test.dart

@@ -66,9 +66,12 @@ void main() {
     WebViewPlatform.instance = platform;
     final session = SchoolSession();
     addTearDown(session.dispose);
+    // A previously authenticated session has already opened its browser.
+    final connectedBrowser = session.web;
     session.connectionState = SchoolConnectionState.connected;
     await session.openTimetable(term: SchoolTerm(72), chooseTerm: true);
     expect(session.needsTermSelection, isTrue);
+    expect(session.web, same(connectedBrowser));
     expect(platform.web.loads, isEmpty);
     expect(session.selectedTerm, SchoolTerm(72));
     expect(session.pendingDraft, isNull);