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>

packages/database/prisma/schema.prisma

@@ -30,10 +30,15 @@ model User {
   createdAt       DateTime @default(now()) @map("created_at")
   updatedAt       DateTime @updatedAt @map("updated_at")
   
+  // Role
+  role            UserRole         @default(USER)
+  
   // Relations
   settings        UserSettings?
   subscription    Subscription?
   courses         Course[]         @relation("AuthoredCourses")
+  enrollments     Enrollment[]
+  lessonProgress  LessonProgress[]
   purchases       Purchase[]
   reviews         Review[]
   generations     CourseGeneration[]
@@ -65,6 +70,12 @@ model UserSettings {
   @@map("user_settings")
 }
 
+enum UserRole {
+  USER
+  MODERATOR
+  ADMIN
+}
+
 // ============================================
 // Subscription & Payments
 // ============================================
@@ -113,7 +124,9 @@ model Subscription {
 enum CourseStatus {
   DRAFT
   GENERATING
+  PENDING_REVIEW
   PUBLISHED
+  REJECTED
   ARCHIVED
 }
 
@@ -130,11 +143,14 @@ model Course {
   // Status
   status          CourseStatus @default(DRAFT)
   
-  // Marketplace (future)
+  // Marketplace
   isPublished     Boolean      @default(false) @map("is_published")
-  price           Decimal?     @db.Decimal(10, 2) // null = private course
+  price           Decimal?     @db.Decimal(10, 2) // null = free course
   currency        String       @default("USD")
   
+  // Author verification — author checked the content and vouches for quality
+  isVerified      Boolean      @default(false) @map("is_verified")
+  
   // Categorization
   categoryId      String?      @map("category_id")
   tags            String[]     @default([])
@@ -155,10 +171,15 @@ model Course {
   createdAt       DateTime     @default(now()) @map("created_at")
   updatedAt       DateTime     @updatedAt @map("updated_at")
   
+  // Moderation
+  moderationNote  String?      @db.Text @map("moderation_note")
+  moderatedAt     DateTime?    @map("moderated_at")
+  
   // Relations
   author          User         @relation("AuthoredCourses", fields: [authorId], references: [id], onDelete: Cascade)
   category        Category?    @relation(fields: [categoryId], references: [id])
   chapters        Chapter[]
+  enrollments     Enrollment[]
   purchases       Purchase[]
   reviews         Review[]
   generation      CourseGeneration?
@@ -360,3 +381,53 @@ model Review {
   @@index([courseId])
   @@map("reviews")
 }
+
+// ============================================
+// Enrollment & Progress
+// ============================================
+
+model Enrollment {
+  id          String    @id @default(uuid())
+  userId      String    @map("user_id")
+  courseId     String    @map("course_id")
+  
+  // Progress
+  progress    Int       @default(0) // 0-100
+  completedAt DateTime? @map("completed_at")
+  
+  // Certificate
+  certificateUrl String? @map("certificate_url")
+  
+  createdAt   DateTime  @default(now()) @map("created_at")
+  updatedAt   DateTime  @updatedAt @map("updated_at")
+  
+  // Relations
+  user        User      @relation(fields: [userId], references: [id], onDelete: Cascade)
+  course      Course    @relation(fields: [courseId], references: [id], onDelete: Cascade)
+  lessons     LessonProgress[]
+  
+  @@unique([userId, courseId])
+  @@index([userId])
+  @@index([courseId])
+  @@map("enrollments")
+}
+
+model LessonProgress {
+  id            String    @id @default(uuid())
+  userId        String    @map("user_id")
+  enrollmentId  String    @map("enrollment_id")
+  lessonId      String    @map("lesson_id")
+  
+  completedAt   DateTime? @map("completed_at")
+  quizScore     Int?      @map("quiz_score") // 0-100
+  
+  createdAt     DateTime  @default(now()) @map("created_at")
+  
+  // Relations
+  user          User       @relation(fields: [userId], references: [id], onDelete: Cascade)
+  enrollment    Enrollment @relation(fields: [enrollmentId], references: [id], onDelete: Cascade)
+  
+  @@unique([userId, lessonId])
+  @@index([enrollmentId])
+  @@map("lesson_progress")
+}