UI rework: modal dialogs, inline lab editing, manual creation, content management

- Dashboard: real stats (groups, students, labs, average grade), labs/groups
  summary lists, no placeholder tile
- Lab page: view + edit combined — metadata form in modal, condition rendered
  as markdown, per-level variant tables with add/edit/delete dialogs,
  level rename/delete, student level/variant selectors with group filter
- Labs list: create-lab dialog with manual level entry (code; title lines)
- Groups: create-group dialog, add-student dialog (auto password, toast card)
- Content: public /learn reader is the single place; admin buttons (new
  article with chapter/section create-or-select, rename/delete chapters and
  sections, move articles between sections, import zip) appear for admins;
  removed separate 'Контент' admin section
- Buttons use btn classes instead of nav-link
- Favicon: generated SVG book icon
- Security: CSRF synchronizer token interceptor (replaced spring-security in
  web which broke logback under nested jars), session regenerated on login,
  hardened session cookie, gateway actuator limited to health,info
- Jackson 3: nullable-safe request DTOs for labs (FAIL_ON_NULL_FOR_PRIMITIVES)
- academic: POST /labs (manual create with levels), level add/rename/delete,
  content chapters/sections CRUD, article create/move/delete endpoints

services/identity-service/src/main/kotlin/ru/ysu/lms/identity/roster/GroupController.kt

@@ -29,6 +29,12 @@ class GroupController(private val groupService: GroupService) {
     @PostMapping
     fun create(@Valid @RequestBody body: CreateGroupRequest): GroupSummary = groupService.create(body)
 
+    @PostMapping("/{id}/students")
+    fun createStudent(
+        @PathVariable id: UUID,
+        @Valid @RequestBody body: CreateStudentRequest,
+    ): Credential = groupService.createStudent(id, body)
+
     @PostMapping("/import")
     fun import(
         @RequestParam("file") file: MultipartFile,

services/identity-service/src/main/kotlin/ru/ysu/lms/identity/roster/GroupService.kt

@@ -31,6 +31,44 @@ class GroupService(
     @Transactional(readOnly = true)
     fun list(): List<GroupSummary> = groups.findAllByOrderByNameAsc().map { summary(it) }
 
+    @Transactional
+    fun createStudent(groupId: UUID, request: CreateStudentRequest): Credential {
+        val group = groups.findById(groupId).orElseThrow { NotFoundException("Группа не найдена") }
+        val studentNo = request.studentNo.trim()
+        if (studentNo.isBlank()) throw BadRequestException("Студенческий номер не может быть пустым")
+        if (students.existsByStudentNo(studentNo)) {
+            throw ConflictException("Студент с номером $studentNo уже существует")
+        }
+        val password = Passwords.generate()
+        val account = accounts.save(
+            Account(
+                login = studentNo,
+                passwordHash = passwordEncoder.encode(password) ?: "",
+                role = LmsRole.STUDENT,
+                mustChangePassword = true,
+                tempPassword = password,
+            ),
+        )
+        val student = students.save(
+            Student(
+                studentNo = studentNo,
+                lastName = request.lastName.trim(),
+                firstName = request.firstName.trim(),
+                middleName = request.middleName.trim(),
+                basis = request.basis.trim(),
+                note = request.note.trim(),
+            ),
+        )
+        student.account = account
+        enrollments.save(Enrollment(group = group, student = student))
+        return Credential(
+            id = account.id.toString(),
+            studentNo = studentNo,
+            fullName = student.fullName,
+            password = password,
+        )
+    }
+
     @Transactional
     fun create(request: CreateGroupRequest): GroupSummary {
         val name = request.name.trim()

services/identity-service/src/main/kotlin/ru/ysu/lms/identity/roster/RosterDtos.kt

@@ -14,6 +14,17 @@ data class CreateGroupRequest(
     val name: String,
 )
 
+data class CreateStudentRequest(
+    @field:NotBlank(message = "Укажите студенческий номер")
+    val studentNo: String,
+    @field:NotBlank(message = "Укажите фамилию")
+    val lastName: String,
+    val firstName: String = "",
+    val middleName: String = "",
+    val basis: String = "",
+    val note: String = "",
+)
+
 data class StudentRow(
     val id: String,
     val studentNo: String,