feat: add absence notification and analytics features

- Implemented AbsenceNotifyView for notifying absence with session details.
- Created AnalyticsView for displaying group analytics and managing students at risk.
- Added ClassAttendanceView for marking attendance in classes.
- Defined new schemas for analytics and attendance in shared package.

apps/backend/prisma/migrations/20260923120000_add_class_sessions_attendance/migration.sql

@@ -0,0 +1,68 @@
+-- CreateEnum
+CREATE TYPE "AttendanceStatus" AS ENUM ('PRESENT', 'ABSENT', 'EXCUSED');
+
+-- AlterTable
+ALTER TABLE "attendees" ADD COLUMN     "notifyToken" TEXT;
+
+-- CreateTable
+CREATE TABLE "class_sessions" (
+    "id" TEXT NOT NULL,
+    "groupId" TEXT NOT NULL,
+    "startsAt" TIMESTAMP(3) NOT NULL,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "class_sessions_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "attendances" (
+    "id" TEXT NOT NULL,
+    "attendeeId" TEXT NOT NULL,
+    "classSessionId" TEXT NOT NULL,
+    "status" "AttendanceStatus" NOT NULL,
+    "markedAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    CONSTRAINT "attendances_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "slot_releases" (
+    "id" TEXT NOT NULL,
+    "attendeeId" TEXT NOT NULL,
+    "classSessionId" TEXT NOT NULL,
+    "isClaimed" BOOLEAN NOT NULL DEFAULT false,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+
+    CONSTRAINT "slot_releases_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "class_sessions_groupId_startsAt_key" ON "class_sessions"("groupId", "startsAt");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "attendances_attendeeId_classSessionId_key" ON "attendances"("attendeeId", "classSessionId");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "slot_releases_attendeeId_classSessionId_key" ON "slot_releases"("attendeeId", "classSessionId");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "attendees_notifyToken_key" ON "attendees"("notifyToken");
+
+-- AddForeignKey
+ALTER TABLE "class_sessions" ADD CONSTRAINT "class_sessions_groupId_fkey" FOREIGN KEY ("groupId") REFERENCES "groups"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "attendances" ADD CONSTRAINT "attendances_attendeeId_fkey" FOREIGN KEY ("attendeeId") REFERENCES "attendees"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "attendances" ADD CONSTRAINT "attendances_classSessionId_fkey" FOREIGN KEY ("classSessionId") REFERENCES "class_sessions"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "slot_releases" ADD CONSTRAINT "slot_releases_attendeeId_fkey" FOREIGN KEY ("attendeeId") REFERENCES "attendees"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "slot_releases" ADD CONSTRAINT "slot_releases_classSessionId_fkey" FOREIGN KEY ("classSessionId") REFERENCES "class_sessions"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- Backfill: tokens de aviso de ausencia para alumnos existentes
+UPDATE "attendees" SET "notifyToken" = gen_random_uuid()::text WHERE "notifyToken" IS NULL;

apps/backend/prisma/migrations/20260923172527_add_attendee_status/migration.sql

@@ -0,0 +1,5 @@
+-- CreateEnum
+CREATE TYPE "AttendeeStatus" AS ENUM ('ACTIVE', 'PAUSED', 'DROPPED');
+
+-- AlterTable
+ALTER TABLE "attendees" ADD COLUMN     "status" "AttendeeStatus" NOT NULL DEFAULT 'ACTIVE';

apps/backend/prisma/models/attendance.prisma

@@ -0,0 +1,50 @@
+// Attendance & class sessions
+
+enum AttendanceStatus {
+  PRESENT
+  ABSENT
+  EXCUSED
+}
+
+model ClassSession {
+  id        String   @id @default(cuid())
+  groupId   String
+  startsAt  DateTime
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  group        Group         @relation(fields: [groupId], references: [id], onDelete: Cascade)
+  attendances  Attendance[]
+  slotReleases SlotRelease[]
+
+  @@unique([groupId, startsAt])
+  @@map("class_sessions")
+}
+
+model Attendance {
+  id             String           @id @default(cuid())
+  attendeeId     String
+  classSessionId String
+  status         AttendanceStatus
+  markedAt       DateTime         @default(now())
+
+  attendee     Attendee     @relation(fields: [attendeeId], references: [id], onDelete: Cascade)
+  classSession ClassSession @relation(fields: [classSessionId], references: [id], onDelete: Cascade)
+
+  @@unique([attendeeId, classSessionId])
+  @@map("attendances")
+}
+
+model SlotRelease {
+  id             String   @id @default(cuid())
+  attendeeId     String
+  classSessionId String
+  isClaimed      Boolean  @default(false)
+  createdAt      DateTime @default(now())
+
+  attendee     Attendee     @relation(fields: [attendeeId], references: [id], onDelete: Cascade)
+  classSession ClassSession @relation(fields: [classSessionId], references: [id], onDelete: Cascade)
+
+  @@unique([attendeeId, classSessionId])
+  @@map("slot_releases")
+}

apps/backend/prisma/models/domain.prisma

@@ -20,6 +20,7 @@ model Group {
   attendees Attendee[]
   payments  Payment[]
   waitlist  GroupWaitlistEntry[]
+  classSessions ClassSession[]
 
   @@map("groups")
 }
@@ -59,8 +60,14 @@ enum Role {
   MEMBER
 }
 
+enum AttendeeStatus {
+  ACTIVE
+  PAUSED
+  DROPPED
+}
+
 model Attendee {
-  id            String   @id @default(cuid())
+  id            String         @id @default(cuid())
   groupId       String
   fullName      String
   email         String?
@@ -68,11 +75,15 @@ model Attendee {
   guardianName  String?
   guardianPhone String?
   notes         String?
-  createdAt     DateTime @default(now())
-  updatedAt     DateTime @updatedAt
+  notifyToken   String?        @unique @default(cuid())
+  status        AttendeeStatus @default(ACTIVE)
+  createdAt     DateTime       @default(now())
+  updatedAt     DateTime       @updatedAt
 
-  group    Group    @relation(fields: [groupId], references: [id], onDelete: Cascade)
-  payments Payment[]
+  group        Group         @relation(fields: [groupId], references: [id], onDelete: Cascade)
+  payments     Payment[]
+  attendances  Attendance[]
+  slotReleases SlotRelease[]
 
   @@index([groupId])
   @@map("attendees")