feat: Sprint 3 — test editing with versioning

Backend:
- migration 003: add parent_id to tests table
- PUT /api/tests/{id}: edit in place if no attempts, create new version otherwise
- GET /api/tests: show only latest versions (no successor)

Frontend:
- TestForm: extracted reusable form component
- TestCreate: refactored to use TestForm
- TestEdit: full edit mode with pre-populated form, version redirect on new version

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/pages/TestEdit/index.tsx

@@ -5,29 +5,91 @@ import {
   EditOutlined,
   PlayCircleOutlined,
 } from '@ant-design/icons'
-import { useQuery } from '@tanstack/react-query'
-import { Alert, Button, Card, Descriptions, List, Space, Spin, Tag, Typography } from 'antd'
+import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
+import { Alert, Button, Card, Descriptions, List, Space, Spin, Tag, Typography, message } from 'antd'
+import { useState } from 'react'
 import { useNavigate, useParams } from 'react-router-dom'
 
-import { Answer, testsApi } from '../../api/tests'
+import { Answer, CreateTestDto, testsApi } from '../../api/tests'
+import TestForm, { TestFormValues } from '../../components/TestForm'
 
 const { Title, Text } = Typography
 
 export default function TestEdit() {
   const { id } = useParams<{ id: string }>()
   const navigate = useNavigate()
+  const queryClient = useQueryClient()
+  const [editMode, setEditMode] = useState(false)
 
   const { data: test, isLoading } = useQuery({
     queryKey: ['tests', id],
     queryFn: () => testsApi.get(Number(id)).then((r) => r.data),
   })
 
+  const { mutate: updateTest, isPending } = useMutation({
+    mutationFn: (data: CreateTestDto) => testsApi.update(Number(id), data).then((r) => r.data),
+    onSuccess: (result) => {
+      queryClient.invalidateQueries({ queryKey: ['tests'] })
+      if (result.is_new_version) {
+        message.success(`Создана новая версия теста (v${result.test.version})`)
+        navigate(`/tests/${result.test.id}/edit`)
+      } else {
+        message.success('Тест обновлён')
+        queryClient.invalidateQueries({ queryKey: ['tests', id] })
+        setEditMode(false)
+      }
+    },
+    onError: (error: unknown) => {
+      const err = error as { response?: { data?: { detail?: string } } }
+      message.error(err.response?.data?.detail || 'Ошибка при сохранении теста')
+    },
+  })
+
   if (isLoading) {
     return <Spin size="large" style={{ display: 'block', margin: '48px auto' }} />
   }
 
   if (!test) return null
 
+  // Режим редактирования — показываем форму с предзаполненными данными
+  if (editMode) {
+    const initialValues: TestFormValues = {
+      title: test.title,
+      description: test.description ?? undefined,
+      passing_score: test.passing_score,
+      has_timer: test.time_limit !== null,
+      time_limit: test.time_limit ?? undefined,
+      allow_navigation_back: test.allow_navigation_back,
+      questions: test.questions.map((q) => ({
+        text: q.text,
+        answers: q.answers.map((a) => ({ text: a.text, is_correct: a.is_correct })),
+      })),
+    }
+
+    const onSubmit = (values: TestFormValues) => {
+      updateTest({
+        title: values.title,
+        description: values.description,
+        passing_score: values.passing_score,
+        time_limit: values.has_timer ? values.time_limit : undefined,
+        allow_navigation_back: values.allow_navigation_back ?? true,
+        questions: values.questions,
+      })
+    }
+
+    return (
+      <TestForm
+        heading={`Редактирование теста — v${test.version}`}
+        initialValues={initialValues}
+        onSubmit={onSubmit}
+        isPending={isPending}
+        submitLabel="Сохранить"
+        onCancel={() => setEditMode(false)}
+      />
+    )
+  }
+
+  // Режим просмотра (вид автора)
   return (
     <div style={{ maxWidth: 820, margin: '0 auto', padding: 24 }}>
       <Space style={{ width: '100%', justifyContent: 'space-between', marginBottom: 16 }}>
@@ -37,8 +99,7 @@ export default function TestEdit() {
         <Space>
           <Button
             icon={<EditOutlined />}
-            disabled
-            title="Редактирование будет доступно в следующем спринте"
+            onClick={() => setEditMode(true)}
           >
             Редактировать
           </Button>