feat: add course catalog, enrollment, progress tracking, quizzes, and reviews

Backend changes:
- Add Enrollment and LessonProgress models to track user progress
- Add UserRole enum (USER, MODERATOR, ADMIN)
- Add course verification and moderation fields
- New CatalogModule: public course browsing, publishing, verification
- New EnrollmentModule: enroll, progress tracking, quiz submission, reviews
- Add quiz generation endpoint to LessonsController

Frontend changes:
- Redesign course viewer: proper course UI with lesson navigation, progress bar
- Add beautiful typography styles for course content (prose-course)
- Fix first-login bug with token exchange retry logic
- New pages: /catalog (public courses), /catalog/[id] (course details), /learning (enrollments)
- Add LessonQuiz component with scoring and results
- Update sidebar navigation: add Catalog and My Learning links
- Add publish/verify buttons in course editor
- Integrate enrollment progress tracking with backend

All courses now support: sequential progression, quiz tests, reviews, ratings,
author verification badges, and full marketplace publishing workflow.

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

apps/api/src/enrollment/enrollment.service.ts

@@ -0,0 +1,140 @@
+import { Injectable, NotFoundException, ConflictException } from '@nestjs/common';
+import { PrismaService } from '../common/prisma/prisma.service';
+
+@Injectable()
+export class EnrollmentService {
+  constructor(private prisma: PrismaService) {}
+
+  async enroll(userId: string, courseId: string): Promise<any> {
+    const existing = await this.prisma.enrollment.findUnique({
+      where: { userId_courseId: { userId, courseId } },
+    });
+    if (existing) throw new ConflictException('Already enrolled');
+
+    return this.prisma.enrollment.create({
+      data: { userId, courseId },
+      include: { course: { select: { id: true, title: true, slug: true } } },
+    });
+  }
+
+  async getUserEnrollments(userId: string): Promise<any> {
+    return this.prisma.enrollment.findMany({
+      where: { userId },
+      include: {
+        course: {
+          include: {
+            author: { select: { id: true, name: true, avatarUrl: true } },
+            _count: { select: { chapters: true } },
+            chapters: { include: { _count: { select: { lessons: true } } } },
+          },
+        },
+      },
+      orderBy: { updatedAt: 'desc' },
+    });
+  }
+
+  async completeLesson(userId: string, courseId: string, lessonId: string): Promise<any> {
+    const enrollment = await this.prisma.enrollment.findUnique({
+      where: { userId_courseId: { userId, courseId } },
+    });
+    if (!enrollment) throw new NotFoundException('Not enrolled in this course');
+
+    const progress = await this.prisma.lessonProgress.upsert({
+      where: { userId_lessonId: { userId, lessonId } },
+      create: {
+        userId,
+        enrollmentId: enrollment.id,
+        lessonId,
+        completedAt: new Date(),
+      },
+      update: {
+        completedAt: new Date(),
+      },
+    });
+
+    await this.recalculateProgress(enrollment.id, courseId);
+    return progress;
+  }
+
+  async saveQuizScore(userId: string, courseId: string, lessonId: string, score: number): Promise<any> {
+    const enrollment = await this.prisma.enrollment.findUnique({
+      where: { userId_courseId: { userId, courseId } },
+    });
+    if (!enrollment) throw new NotFoundException('Not enrolled in this course');
+
+    return this.prisma.lessonProgress.upsert({
+      where: { userId_lessonId: { userId, lessonId } },
+      create: {
+        userId,
+        enrollmentId: enrollment.id,
+        lessonId,
+        quizScore: score,
+        completedAt: new Date(),
+      },
+      update: { quizScore: score },
+    });
+  }
+
+  async getProgress(userId: string, courseId: string): Promise<any> {
+    return this.prisma.enrollment.findUnique({
+      where: { userId_courseId: { userId, courseId } },
+      include: { lessons: true },
+    });
+  }
+
+  async createReview(userId: string, courseId: string, rating: number, title?: string, content?: string): Promise<any> {
+    const review = await this.prisma.review.upsert({
+      where: { userId_courseId: { userId, courseId } },
+      create: { userId, courseId, rating, title, content },
+      update: { rating, title, content },
+    });
+
+    // Recalculate avg rating
+    const result = await this.prisma.review.aggregate({
+      where: { courseId, isApproved: true },
+      _avg: { rating: true },
+    });
+    if (result._avg.rating !== null) {
+      await this.prisma.course.update({
+        where: { id: courseId },
+        data: { averageRating: result._avg.rating },
+      });
+    }
+
+    return review;
+  }
+
+  async getCourseReviews(courseId: string, page = 1, limit = 20): Promise<any> {
+    const skip = (page - 1) * limit;
+    const [reviews, total] = await Promise.all([
+      this.prisma.review.findMany({
+        where: { courseId, isApproved: true },
+        include: { user: { select: { id: true, name: true, avatarUrl: true } } },
+        orderBy: { createdAt: 'desc' },
+        skip,
+        take: limit,
+      }),
+      this.prisma.review.count({ where: { courseId, isApproved: true } }),
+    ]);
+    return { data: reviews, meta: { page, limit, total } };
+  }
+
+  private async recalculateProgress(enrollmentId: string, courseId: string): Promise<void> {
+    const totalLessons = await this.prisma.lesson.count({
+      where: { chapter: { courseId } },
+    });
+    const completedLessons = await this.prisma.lessonProgress.count({
+      where: { enrollmentId, completedAt: { not: null } },
+    });
+
+    const progress = totalLessons > 0 ? Math.round((completedLessons / totalLessons) * 100) : 0;
+
+    await this.prisma.enrollment.update({
+      where: { id: enrollmentId },
+      data: {
+        progress,
+        completedAt: progress >= 100 ? new Date() : null,
+      },
+    });
+  }
+}