feat: Afficher la couleur des matières dans l'emploi du temps élève et parent

L'admin pouvait attribuer une couleur à chaque matière, mais cette
couleur n'était utilisée que dans la vue admin de l'emploi du temps.
Les APIs élève et parent ne renvoyaient pas cette information, ce qui
donnait un affichage générique (gris/bleu) pour tous les créneaux.

L'API renvoie désormais subjectColor dans chaque créneau, et les vues
jour/semaine/widget/détails affichent la bordure colorée correspondante.
Le marqueur "Prochain cours" conserve sa priorité visuelle via une
surcharge CSS variable.

backend/src/Scolarite/Application/Query/GetChildrenSchedule/GetChildrenScheduleHandler.php

@@ -111,13 +111,14 @@ final readonly class GetChildrenScheduleHandler
             array_map(static fn (ResolvedScheduleSlot $s): string => (string) $s->teacherId, $slots),
         ));
 
-        $subjectNames = $this->displayReader->subjectNames($tenantId, ...$subjectIds);
+        $subjects = $this->displayReader->subjectDisplay($tenantId, ...$subjectIds);
         $teacherNames = $this->displayReader->teacherNames($tenantId, ...$teacherIds);
 
         return array_map(
             static fn (ResolvedScheduleSlot $s): StudentScheduleSlotDto => StudentScheduleSlotDto::fromResolved(
                 $s,
-                $subjectNames[(string) $s->subjectId] ?? '',
+                $subjects[(string) $s->subjectId]['name'] ?? '',
+                $subjects[(string) $s->subjectId]['color'] ?? null,
                 $teacherNames[(string) $s->teacherId] ?? '',
             ),
             $slots,

backend/src/Scolarite/Application/Query/GetStudentSchedule/GetStudentScheduleHandler.php

@@ -74,13 +74,14 @@ final readonly class GetStudentScheduleHandler
             array_map(static fn (ResolvedScheduleSlot $s): string => (string) $s->teacherId, $slots),
         ));
 
-        $subjectNames = $this->displayReader->subjectNames($tenantId, ...$subjectIds);
+        $subjects = $this->displayReader->subjectDisplay($tenantId, ...$subjectIds);
         $teacherNames = $this->displayReader->teacherNames($tenantId, ...$teacherIds);
 
         return array_map(
             static fn (ResolvedScheduleSlot $s): StudentScheduleSlotDto => StudentScheduleSlotDto::fromResolved(
                 $s,
-                $subjectNames[(string) $s->subjectId] ?? '',
+                $subjects[(string) $s->subjectId]['name'] ?? '',
+                $subjects[(string) $s->subjectId]['color'] ?? null,
                 $teacherNames[(string) $s->teacherId] ?? '',
             ),
             $slots,

backend/src/Scolarite/Application/Query/GetStudentSchedule/StudentScheduleSlotDto.php

@@ -16,6 +16,7 @@ final readonly class StudentScheduleSlotDto
         public string $endTime,
         public string $subjectId,
         public string $subjectName,
+        public ?string $subjectColor,
         public string $teacherId,
         public string $teacherName,
         public ?string $room,
@@ -27,6 +28,7 @@ final readonly class StudentScheduleSlotDto
     public static function fromResolved(
         ResolvedScheduleSlot $slot,
         string $subjectName,
+        ?string $subjectColor,
         string $teacherName,
     ): self {
         return new self(
@@ -37,6 +39,7 @@ final readonly class StudentScheduleSlotDto
             endTime: $slot->timeSlot->endTime,
             subjectId: (string) $slot->subjectId,
             subjectName: $subjectName,
+            subjectColor: $subjectColor,
             teacherId: (string) $slot->teacherId,
             teacherName: $teacherName,
             room: $slot->room,