feat: certificate page for print, API certificate data, AI prompts for full lessons

- Certificate: page /certificate/[courseId] with print-friendly design, GET /certificates/:courseId/data
- Buttons 'Получить сертификат' open certificate page instead of data-URL
- AI: prompts for longer courses (more chapters/lessons), full detailed lesson content with examples (1000–1500+ words)

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/api/src/certificates/certificates.controller.ts

@@ -10,6 +10,12 @@ import { User } from '@coursecraft/database';
 export class CertificatesController {
   constructor(private certificatesService: CertificatesService) {}
 
+  @Get(':courseId/data')
+  @ApiOperation({ summary: 'Get certificate data for display/print page' })
+  async getCertificateData(@Param('courseId') courseId: string, @CurrentUser() user: User) {
+    return this.certificatesService.getCertificateData(user.id, courseId);
+  }
+
   @Get(':courseId')
   @ApiOperation({ summary: 'Generate certificate for completed course' })
   async getCertificate(@Param('courseId') courseId: string, @CurrentUser() user: User): Promise<any> {

apps/api/src/certificates/certificates.service.ts

@@ -5,7 +5,11 @@ import { PrismaService } from '../common/prisma/prisma.service';
 export class CertificatesService {
   constructor(private prisma: PrismaService) {}
 
-  async generateCertificate(userId: string, courseId: string): Promise<any> {
+  async getCertificateData(userId: string, courseId: string): Promise<{
+    userName: string;
+    courseTitle: string;
+    completedAt: string;
+  }> {
     const enrollment = await this.prisma.enrollment.findUnique({
       where: { userId_courseId: { userId, courseId } },
       include: { course: true, user: true },
@@ -14,19 +18,27 @@ export class CertificatesService {
     if (!enrollment) throw new NotFoundException('Not enrolled');
     if (!enrollment.completedAt) throw new Error('Course not completed yet');
 
-    // Generate certificate HTML (in production, render to PDF using puppeteer or similar)
+    return {
+      userName: enrollment.user.name || enrollment.user.email || 'Слушатель',
+      courseTitle: enrollment.course.title,
+      completedAt: new Date(enrollment.completedAt).toISOString(),
+    };
+  }
+
+  async generateCertificate(userId: string, courseId: string): Promise<any> {
+    const data = await this.getCertificateData(userId, courseId);
+    const completionDate = new Date(data.completedAt);
+
     const certificateHtml = this.renderCertificateHTML(
-      enrollment.user.name || enrollment.user.email,
-      enrollment.course.title,
-      new Date(enrollment.completedAt)
+      data.userName,
+      data.courseTitle,
+      completionDate
     );
 
-    // In production: save to S3/R2 and return URL
-    // For now, return inline HTML
     const certificateUrl = `data:text/html;base64,${Buffer.from(certificateHtml).toString('base64')}`;
 
     await this.prisma.enrollment.update({
-      where: { id: enrollment.id },
+      where: { userId_courseId: { userId, courseId } },
       data: { certificateUrl },
     });
 
@@ -48,7 +60,7 @@ export class CertificatesService {
       min-height: 100vh;
       display: flex;
       align-items: center;
-      justify-center;
+      justify-content: center;
     }
     .certificate {
       background: white;