fix(dev): bind frontend to 127.0.0.1:8080 and avoid EACCES\nfix(backend): bind server to 127.0.0.1:8081, add permissive CORS whitelist\nfix(auth): login form UX remove default username, clarify placeholder, add test account autofill\nchore(api): set frontend API_BASE_URL to 127.0.0.1:8081\nrefactor(assignments): lifecycle/state logic and archive endpoint\nfeat(analytics): add exam stats endpoint and client method\nchore(lint): add eslint configs

backend/prisma/schema.prisma

@@ -328,9 +328,11 @@ model Exam {
   id                String     @id @default(uuid()) @db.VarChar(36)
   subjectId         String     @map("subject_id") @db.VarChar(36)
   title             String     @db.VarChar(200)
+  examType          String     @default("Uncategorized") @map("exam_type") @db.VarChar(50) // e.g. Midterm, Final, Unit, Weekly
   totalScore        Decimal    @map("total_score") @default(0) @db.Decimal(5, 1)
   suggestedDuration Int        @map("suggested_duration")
   status            ExamStatus @default(Draft)
+  description       String?    @db.Text
   
   createdAt         DateTime   @default(now()) @map("created_at")
   createdBy         String     @map("created_by") @db.VarChar(36)
@@ -402,7 +404,8 @@ model Assignment {
   endTime             DateTime            @map("end_time")
   allowLateSubmission Boolean             @map("allow_late_submission") @default(false)
   autoScoreEnabled    Boolean             @map("auto_score_enabled") @default(true)
-  
+  status              AssignmentStatus    @default(Active)
+
   createdAt           DateTime            @default(now()) @map("created_at")
   createdBy           String              @map("created_by") @db.VarChar(36)
   updatedAt           DateTime            @updatedAt @map("updated_at")
@@ -425,6 +428,7 @@ model StudentSubmission {
   assignmentId     String             @map("assignment_id") @db.VarChar(36)
   studentId        String             @map("student_id") @db.VarChar(36)
   submissionStatus SubmissionStatus   @map("submission_status") @default(Pending)
+  startedAt        DateTime?          @map("started_at")
   submitTime       DateTime?          @map("submit_time")
   timeSpentSeconds Int?               @map("time_spent_seconds")
   totalScore       Decimal?           @map("total_score") @db.Decimal(5, 1)
@@ -478,6 +482,11 @@ enum SubmissionStatus {
   Graded
 }
 
+enum AssignmentStatus {
+  Active
+  Archived
+}
+
 enum JudgementResult {
   Correct
   Incorrect