Stage 1.5: categories, enrollment expiry, access log, bulk grant, user page

prisma/schema.prisma

@@ -24,13 +24,15 @@ model User {
   createdAt     DateTime  @default(now())
   updatedAt     DateTime  @updatedAt
 
-  sessions    Session[]
-  accounts    Account[]
-  enrollments CourseEnrollment[]
-  progress    LessonProgress[]
-  submissions HomeworkSubmission[]
-  comments    LessonComment[]
-  feedbacks   HomeworkFeedback[]
+  sessions        Session[]
+  accounts        Account[]
+  enrollments     CourseEnrollment[]
+  progress        LessonProgress[]
+  submissions     HomeworkSubmission[]
+  comments        LessonComment[]
+  feedbacks       HomeworkFeedback[]
+  accessLogs      AccessLog[] @relation("AccessLogUser")
+  adminAccessLogs AccessLog[] @relation("AccessLogAdmin")
 }
 
 model Session {
@@ -77,6 +79,16 @@ model Verification {
 // LMS core tables
 // ─────────────────────────────────────────────
 
+model Category {
+  id        String   @id @default(cuid())
+  title     String
+  slug      String   @unique
+  order     Int      @default(0)
+  createdAt DateTime @default(now())
+
+  courses Course[]
+}
+
 model Course {
   id          String   @id @default(cuid())
   slug        String   @unique
@@ -85,11 +97,14 @@ model Course {
   coverImage  String?
   published   Boolean  @default(false)
   order       Int      @default(0)
+  categoryId  String?
   createdAt   DateTime @default(now())
   updatedAt   DateTime @updatedAt
 
+  category    Category?          @relation(fields: [categoryId], references: [id], onDelete: SetNull)
   modules     Module[]
   enrollments CourseEnrollment[]
+  accessLogs  AccessLog[]
 }
 
 model Module {
@@ -137,7 +152,8 @@ model LessonFile {
 model CourseEnrollment {
   userId     String
   courseId   String
-  enrolledAt DateTime @default(now())
+  enrolledAt DateTime  @default(now())
+  expiresAt  DateTime?
 
   user   User   @relation(fields: [userId], references: [id], onDelete: Cascade)
   course Course @relation(fields: [courseId], references: [id], onDelete: Cascade)
@@ -145,6 +161,21 @@ model CourseEnrollment {
   @@id([userId, courseId])
 }
 
+model AccessLog {
+  id          String   @id @default(cuid())
+  courseId    String
+  userId      String
+  action      String   // "granted" | "revoked"
+  method      String   @default("manual")
+  grantedById String?
+  note        String?
+  createdAt   DateTime @default(now())
+
+  course      Course @relation(fields: [courseId], references: [id], onDelete: Cascade)
+  user        User   @relation("AccessLogUser", fields: [userId], references: [id], onDelete: Cascade)
+  grantedBy   User?  @relation("AccessLogAdmin", fields: [grantedById], references: [id], onDelete: SetNull)
+}
+
 model LessonProgress {
   userId      String
   lessonId    String