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/test/analytics-risk.test.ts

@@ -0,0 +1,79 @@
+import { describe, expect, it } from 'bun:test';
+import {
+  classifyRisk,
+  lastAttendedAt,
+  monthlyAttendanceRate,
+  trailingAbsentStreak,
+} from '@/modules/analytics/lib/risk';
+
+const day = 24 * 60 * 60 * 1000;
+const at = (offsetDays: number) => new Date(Date.now() - offsetDays * day);
+
+function entry(status: 'PRESENT' | 'ABSENT' | 'EXCUSED', offsetDays: number) {
+  return { status, occurredAt: at(offsetDays) };
+}
+
+describe('trailingAbsentStreak', () => {
+  it('devuelve 0 sin registros', () => {
+    expect(trailingAbsentStreak([])).toBe(0);
+  });
+
+  it('cuenta ausencias consecutivas sin justificar desde la más reciente', () => {
+    expect(trailingAbsentStreak([entry('ABSENT', 0)])).toBe(1);
+    expect(trailingAbsentStreak([entry('ABSENT', 0), entry('ABSENT', 7), entry('ABSENT', 14)])).toBe(3);
+  });
+
+  it('rompe la cadena con PRESENT o EXCUSED', () => {
+    expect(
+      trailingAbsentStreak([entry('ABSENT', 0), entry('ABSENT', 7), entry('PRESENT', 14)]),
+    ).toBe(2);
+    expect(trailingAbsentStreak([entry('EXCUSED', 0), entry('ABSENT', 7)])).toBe(0);
+    expect(trailingAbsentStreak([entry('PRESENT', 0)])).toBe(0);
+  });
+});
+
+describe('lastAttendedAt', () => {
+  it('devuelve la clase PRESENT más reciente', () => {
+    const result = lastAttendedAt([
+      entry('PRESENT', 0),
+      entry('ABSENT', 7),
+      entry('ABSENT', 14),
+    ]);
+    expect(result).not.toBeNull();
+    expect(result?.getTime()).toBe(at(0).getTime());
+  });
+
+  it('devuelve null si nunca asistió', () => {
+    expect(lastAttendedAt([entry('ABSENT', 0), entry('EXCUSED', 7)])).toBeNull();
+    expect(lastAttendedAt([])).toBeNull();
+  });
+});
+
+describe('monthlyAttendanceRate', () => {
+  it('razón de PRESENT sobre el total de sesiones', () => {
+    expect(monthlyAttendanceRate([entry('PRESENT', 0), entry('PRESENT', 7), entry('ABSENT', 14)], 5)).toBe(40);
+  });
+
+  it('devuelve 0 sin sesiones o sin presentes', () => {
+    expect(monthlyAttendanceRate([], 3)).toBe(0);
+    expect(monthlyAttendanceRate([entry('ABSENT', 0)], 3)).toBe(0);
+  });
+});
+
+describe('classifyRisk', () => {
+  it('HIGH con 3 o más ausencias consecutivas', () => {
+    expect(classifyRisk(3, 80)).toBe('HIGH');
+    expect(classifyRisk(5, 20)).toBe('HIGH');
+  });
+
+  it('MEDIUM con 2 ausencias consecutivas o asistencia menor al 50%', () => {
+    expect(classifyRisk(2, 90)).toBe('MEDIUM');
+    expect(classifyRisk(1, 40)).toBe('MEDIUM');
+    expect(classifyRisk(2, 40)).toBe('MEDIUM');
+  });
+
+  it('sin riesgo si no cumple ningún umbral', () => {
+    expect(classifyRisk(1, 60)).toBeNull();
+    expect(classifyRisk(0, 60)).toBeNull();
+  });
+});