feat: 多班级版 v2.0 - Go后端重写 + 43轮代码审查

- 后端从 Python FastAPI 重写为 Go Gin（端口 56789）
- 多班级完全隔离
- 超级管理员独立登录
- 课代表作业管理、排行榜分项排行
- 角色加减分上下限可配置
- 家长改密功能（可开关）
- 周度/月度重置功能
- MySQL 5.7 兼容
- 43轮代码审查+全部修复
- Apache 2.0 许可证

frontend/admin/cadre_homework.php

@@ -0,0 +1,125 @@
+<?php
+/**
+ * 多班级版班级管理系统 - 课代表作业管理页
+ * 
+ * 开发者: Canglan
+ * 联系方式: admin@sea-studio.top
+ * 版权归属: Sea Network Technology Studio
+ * 许可证: Apache License 2.0
+ * 
+ * 版权所有 © Sea Network Technology Studio
+ */
+
+$page_title = '作业管理';
+require_once __DIR__ . '/../config.php';
+
+if (!isset($_SESSION['user_id']) || $_SESSION['user_type'] !== 'admin') {
+    header('Location: /index.php');
+    exit();
+}
+
+$role = $_SESSION['role'] ?? '';
+if ($role !== '课代表') {
+    header('Location: /admin/dashboard.php');
+    exit();
+}
+
+require_once __DIR__ . '/../includes/header.php';
+require_once __DIR__ . '/../includes/nav.php';
+?>
+
+<div class="container">
+    <div class="page-header">
+        <h2>作业管理</h2>
+        <p class="text-muted">课代表可管理所代表科目的作业缺交情况</p>
+    </div>
+
+    <div class="card">
+        <div class="action-bar">
+            <div class="action-buttons">
+                <button class="btn btn-primary" onclick="showPublishModal()">发布作业</button>
+            </div>
+        </div>
+        <div class="table-wrapper">
+            <table class="table">
+                <thead>
+                    <tr>
+                        <th>作业标题</th>
+                        <th>科目</th>
+                        <th>截止日期</th>
+                        <th>描述</th>
+                        <th>操作</th>
+                    </tr>
+                </thead>
+                <tbody id="homeworkList">
+                    <tr><td colspan="5" style="text-align:center;">加载中...</td></tr>
+                </tbody>
+            </table>
+        </div>
+        <div class="pagination" id="pagination" style="display:none;">
+            <button class="btn btn-sm" id="prevBtn" onclick="changePage(-1)">上一页</button>
+            <span id="pageInfo">1 / 1</span>
+            <button class="btn btn-sm" id="nextBtn" onclick="changePage(1)">下一页</button>
+        </div>
+    </div>
+</div>
+
+<!-- 发布作业模态框 -->
+<div id="publishModal" class="modal">
+    <div class="modal-content">
+        <div class="modal-header">
+            <h3>发布作业</h3>
+            <button class="modal-close" onclick="closeModal('publishModal')">&times;</button>
+        </div>
+        <form id="publishForm" onsubmit="event.preventDefault(); submitHomework()">
+            <div class="form-group">
+                <label>作业标题 <span style="color:red;">*</span></label>
+                <input type="text" id="hwTitle" required placeholder="例如：第三章练习">
+            </div>
+            <div class="form-group">
+                <label>截止日期 <span style="color:red;">*</span></label>
+                <input type="date" id="hwDeadline" required value="<?php echo date('Y-m-d'); ?>">
+            </div>
+            <div class="form-group">
+                <label>描述</label>
+                <textarea id="hwDescription" rows="3" placeholder="选填，作业详细说明"></textarea>
+            </div>
+            <div class="modal-footer">
+                <button type="submit" class="btn btn-primary">发布</button>
+                <button type="button" class="btn" onclick="closeModal('publishModal')">取消</button>
+            </div>
+        </form>
+    </div>
+</div>
+
+<!-- 缺交登记模态框 -->
+<div id="absentModal" class="modal">
+    <div class="modal-content">
+        <div class="modal-header">
+            <h3>登记缺交学生</h3>
+            <button class="modal-close" onclick="closeModal('absentModal')">&times;</button>
+        </div>
+        <div id="absentStudentList"></div>
+        <div class="modal-footer">
+            <button class="btn btn-primary" onclick="submitAbsent()">提交缺交记录</button>
+            <button class="btn" onclick="closeModal('absentModal')">取消</button>
+        </div>
+    </div>
+</div>
+
+<style>
+.pagination {
+    display: flex;
+    justify-content: center;
+    align-items: center;
+    gap: 15px;
+    margin-top: 15px;
+    padding: 10px 0;
+}
+.pagination .btn { padding: 6px 16px; font-size: 13px; }
+.pagination span { color: #666; font-size: 14px; }
+</style>
+
+<script src="/assets/js/cadre-homework.js"></script>
+
+<?php require_once __DIR__ . '/../includes/footer.php'; ?>