feat: Permettre à l'élève de consulter ses notes et moyennes

L'élève avait accès à ses compétences mais pas à ses notes numériques.
Cette fonctionnalité lui donne une vue complète de sa progression scolaire
avec moyennes par matière, détail par évaluation, statistiques de classe,
et un mode "découverte" pour révéler ses notes à son rythme (FR14, FR15).

Les notes ne sont visibles qu'après publication par l'enseignant, ce qui
garantit que l'élève les découvre avant ses parents (délai 24h story 6.7).

frontend/src/lib/components/organisms/Dashboard/DashboardStudent.svelte

@@ -2,8 +2,12 @@
 	import type { DemoData } from '$types';
 	import type { ScheduleSlot } from '$lib/features/schedule/api/schedule';
 	import type { StudentHomework, StudentHomeworkDetail } from '$lib/features/homework/api/studentHomework';
+	import type { StudentGrade } from '$lib/features/grades/api/studentGrades';
 	import { fetchDaySchedule, fetchNextClass } from '$lib/features/schedule/api/schedule';
 	import { fetchStudentHomework, fetchHomeworkDetail } from '$lib/features/homework/api/studentHomework';
+	import type { StudentAverages } from '$lib/features/grades/api/studentGrades';
+	import { fetchMyGrades, fetchMyAverages } from '$lib/features/grades/api/studentGrades';
+	import { isGradeNew, markGradesSeen } from '$lib/features/grades/stores/gradePreferences.svelte';
 	import HomeworkDetail from '$lib/components/organisms/StudentHomework/HomeworkDetail.svelte';
 	import { recordSync } from '$lib/features/schedule/stores/scheduleCache.svelte';
 	import { getHomeworkStatuses } from '$lib/features/homework/stores/homeworkStatus.svelte';
@@ -36,6 +40,11 @@
 	let studentHomeworks = $state<StudentHomework[]>([]);
 	let homeworkLoading = $state(false);
 
+	// Grades widget state
+	let recentGrades = $state<StudentGrade[]>([]);
+	let studentAverages = $state<StudentAverages | null>(null);
+	let gradesLoading = $state(false);
+
 	let hwStatuses = $derived(getHomeworkStatuses());
 
 	let pendingHomeworks = $derived(
@@ -88,6 +97,33 @@
 		}
 	}
 
+	let gradeSeenTimerId: number | null = null;
+
+	async function loadGrades() {
+		gradesLoading = true;
+
+		try {
+			const [all, avgs] = await Promise.all([fetchMyGrades(), fetchMyAverages()]);
+			recentGrades = all.slice(0, 5);
+			studentAverages = avgs;
+
+			const ids = all.map((g) => g.id);
+			gradeSeenTimerId = window.setTimeout(() => markGradesSeen(ids), 3000);
+		} catch {
+			// Silently fail on dashboard widget
+		} finally {
+			gradesLoading = false;
+		}
+	}
+
+	function gradeColor(value: number | null, scale: number): string {
+		if (value === null || scale <= 0) return '#6b7280';
+		const normalized = (value / scale) * 20;
+		if (normalized >= 14) return '#22c55e';
+		if (normalized >= 10) return '#f59e0b';
+		return '#ef4444';
+	}
+
 	// Homework detail modal
 	let selectedHomeworkDetail = $state<StudentHomeworkDetail | null>(null);
 
@@ -116,6 +152,10 @@
 		if (!isEleve) return;
 		void loadTodaySchedule();
 		void loadHomeworks();
+		void loadGrades();
+		return () => {
+			if (gradeSeenTimerId !== null) window.clearTimeout(gradeSeenTimerId);
+		};
 	});
 </script>
 
@@ -179,11 +219,51 @@
 		<!-- Notes Section -->
 		<DashboardSection
 			title="Mes notes"
-			subtitle={hasRealData ? "Dernières notes" : undefined}
-			isPlaceholder={!hasRealData}
+			subtitle={isEleve ? "Dernières notes" : (hasRealData ? "Dernières notes" : undefined)}
+			isPlaceholder={!isEleve && !hasRealData}
 			placeholderMessage={isMinor ? "Tes notes apparaîtront ici" : "Vos notes apparaîtront ici"}
 		>
-			{#if hasRealData}
+			{#if isEleve}
+				{#if gradesLoading}
+					<SkeletonList items={3} message="Chargement des notes..." />
+				{:else if recentGrades.length === 0}
+					<p class="empty-grades">Aucune note publiée</p>
+				{:else}
+					{#if studentAverages?.generalAverage != null}
+						<div class="widget-general-avg">
+							<span class="widget-avg-label">Moyenne générale</span>
+							<span class="widget-avg-value" style:color={gradeColor(studentAverages.generalAverage, 20)}>
+								{studentAverages.generalAverage.toFixed(1)}/20
+							</span>
+						</div>
+					{/if}
+					<ul class="grades-list">
+						{#each recentGrades as grade}
+							<li class="grade-item">
+								<div class="grade-header">
+									<span class="grade-subject">{grade.subjectName ?? 'Matière'}</span>
+									{#if isGradeNew(grade.id)}
+										<span class="grade-badge-new">Nouveau</span>
+									{/if}
+									{#if grade.status === 'graded' && grade.value != null}
+										<span class="grade-value" style:color={gradeColor(grade.value, grade.gradeScale)}>
+											{grade.value}/{grade.gradeScale}
+										</span>
+									{:else if grade.status === 'absent'}
+										<span class="grade-value" style:color="#f59e0b">Absent</span>
+									{:else if grade.status === 'dispensed'}
+										<span class="grade-value" style:color="#6b7280">Dispensé</span>
+									{/if}
+								</div>
+								<span class="grade-eval">{grade.evaluationTitle}</span>
+							</li>
+						{/each}
+					</ul>
+					<a href="/dashboard/student-grades" class="view-all-link">
+						Voir toutes les notes →
+					</a>
+				{/if}
+			{:else if hasRealData}
 				{#if isLoading}
 					<SkeletonList items={3} message="Chargement des notes..." />
 				{:else}
@@ -406,6 +486,45 @@
 		color: #6b7280;
 	}
 
+	.grade-badge-new {
+		font-size: 0.5625rem;
+		padding: 0.0625rem 0.375rem;
+		background: #eff6ff;
+		color: #2563eb;
+		border-radius: 1rem;
+		font-weight: 600;
+		text-transform: uppercase;
+	}
+
+	.empty-grades {
+		margin: 0;
+		text-align: center;
+		padding: 1rem;
+		color: #6b7280;
+		font-size: 0.875rem;
+	}
+
+	.widget-general-avg {
+		display: flex;
+		justify-content: space-between;
+		align-items: center;
+		padding: 0.5rem 0.75rem;
+		background: #f0fdf4;
+		border: 1px solid #bbf7d0;
+		border-radius: 0.5rem;
+		margin-bottom: 0.5rem;
+	}
+
+	.widget-avg-label {
+		font-size: 0.75rem;
+		color: #6b7280;
+	}
+
+	.widget-avg-value {
+		font-size: 1rem;
+		font-weight: 700;
+	}
+
 	/* Homework List */
 	.homework-list {
 		list-style: none;