feat(modules): module topics for student form, admin CRUD with pagination

- db: modules table (name, lessons_count) + entries.module_id (ON DELETE SET NULL), migration + idempotent startup ensure
- api: GET /api/modules (public, search + limit/offset, entries_count), POST/PUT/DELETE (admin, audit-logged)
- entries: accept/validate module_id on create/update, return module_name, module_id filter
- backup/restore: include modules and entries.module_id
- student form: required module select, hidden while no modules exist
- admin: modules.html + js/modules.js list with pagination, search, create/edit/delete modal
- journal: module filter, module select in edit modal, module badge, CSV column

public/js/index.js

@@ -4,6 +4,8 @@ const preview = document.getElementById('preview');
 const placeholderSrc = preview.src;
 const removePhotoBtn = document.getElementById('removePhotoBtn');
 const groupInput = document.getElementById('groupInput');
+const moduleInput = document.getElementById('moduleInput');
+const moduleField = document.getElementById('moduleField');
 const toast = document.getElementById('toast');
 const camVideo = document.getElementById('camVideo');
 const camCanvas = document.getElementById('camCanvas');
@@ -133,6 +135,23 @@ if (params.get('nameInput')) {
 }
 
 (async () => {
+  try {
+    const mRes = await fetch(`${API}/api/modules`);
+    if (mRes.ok) {
+      const mData = await mRes.json();
+      const list = mData.modules || [];
+      if (list.length) {
+        list.forEach(m => {
+          const opt = document.createElement('option');
+          opt.value = m.id;
+          opt.textContent = m.lessons_count > 0 ? `${m.name} · ${m.lessons_count} зан.` : m.name;
+          moduleInput.appendChild(opt);
+        });
+        moduleInput.required = true;
+        moduleField.style.display = '';
+      }
+    }
+  } catch (e) { /* ignore */ }
   const res = await fetch(`${API}/api/students`);
   const students = await res.json();
   const me = studentName ? students.find(s => s.name === studentName) : null;
@@ -219,6 +238,12 @@ form.addEventListener('submit', async (e) => {
     setTimeout(() => toast.classList.remove('show', 'error'), 3200);
     return;
   }
+  if (moduleField.style.display !== 'none' && !moduleInput.value) {
+    toast.textContent = 'Выберите тему модуля';
+    toast.classList.add('show', 'error');
+    setTimeout(() => toast.classList.remove('show', 'error'), 3200);
+    return;
+  }
   const btn = document.getElementById('submitBtn');
   btn.disabled = true;
   btn.textContent = 'Отправка...';
@@ -228,6 +253,7 @@ form.addEventListener('submit', async (e) => {
   selectedFiles.forEach(f => fd.append('files', f, f.name));
   fd.append('student_name', studentName || document.getElementById('nameInput').value);
   fd.append('group_id', groupInput.value);
+  fd.append('module_id', moduleInput.value);
   fd.append('description', document.getElementById('descInput').value);
   fd.append('website', document.getElementById('hpWebsite').value);