fix: harden school imports and add optional feedback diagnostics

mobile/lib/features/school/undergraduate/activity_data.dart

@@ -21,6 +21,10 @@ List<UndergraduateActivity> parseActivityData(
     r'new\s+TaskActivity\s*\((.*?)\)\s*;',
     dotAll: true,
   ).allMatches(script).toList();
+  if (RegExp(r'\bnew\s+TaskActivity\s*\(').allMatches(script).length !=
+      matches.length) {
+    throw const FormatException('课程活动声明不完整');
+  }
   final result = <UndergraduateActivity>[];
   for (var i = 0; i < matches.length; i++) {
     final m = matches[i], args = _strings(m[1]!);
@@ -48,9 +52,17 @@ List<UndergraduateActivity> parseActivityData(
     final assignments = RegExp(r'\bindex\s*=\s*([^;]+);')
         .allMatches(body)
         .toList();
-    final appends = RegExp(
+    final appendPattern = RegExp(
       r'table\d+\.activities\[index\]\s*\[[^;]+?\]\s*=\s*activity\s*;',
-    ).allMatches(body).length;
+    );
+    final appends = appendPattern.allMatches(body).length;
+    final unconsumed = body
+        .replaceAll(appendPattern, '')
+        .replaceAll(RegExp(r'\bindex\s*=\s*[^;]+;'), '');
+    if (RegExp(r'\btable\d+\.activities\s*\[|\bindex\s*=')
+        .hasMatch(unconsumed)) {
+      throw const FormatException('存在无法识别的课程节次赋值');
+    }
     if (assignments.isEmpty || assignments.length != appends) {
       throw const FormatException('课程节次赋值不完整');
     }