Preserve courses with pending rooms and report precise graduate import errors

mobile/test/school/recognized_timetable_test.dart

@@ -16,6 +16,31 @@ String fixture() {
 
 void main() {
   final url = Uri.parse('https://yjsjy.uestc.edu.cn/pyxx/pygl/xskbcx/index/1');
+  test('graduate course identifiers need not be numeric and missing rooms remain explicit', () {
+    final body = fixture()
+        .replaceAll('101/示例', 'G101/示例')
+        .replaceAll('/示例楼B212', '/');
+    final draft = SchoolPageAdapter().extract(body, url);
+    expect(draft.courses, hasLength(4));
+    final pending = draft.courses.where((c) => c.name.contains('集成电路'));
+    expect(pending.every((c) => c.room == '教室待定'), isTrue);
+    expect(pending.every((c) => c.notes.contains('学校未提供教室')), isTrue);
+  });
+  test('graduate malformed record provides a safe specific reason', () {
+    expect(
+      () => SchoolPageAdapter().extract(
+        fixture().replaceFirst('1-3周', '未知周'),
+        url,
+      ),
+      throwsA(
+        isA<UnsupportedSchoolLayout>().having(
+          (e) => e.toString(),
+          'reason',
+          contains('上课周次'),
+        ),
+      ),
+    );
+  });
   test('school DOM merges week segments without losing full metadata or evening periods', () {
     final draft = SchoolPageAdapter().extract(fixture(), url);
     expect(draft.courses.length, 4);