feat(absences) : avancement module absences + suppression du portail client

Deux lots regroupés sur la branche feat/absence-management.

Suppression complète du portail client :
- retire ROLE_CLIENT (security.yaml) ; User::getRoles() ajoute toujours ROLE_USER
- supprime l'entité ClientTicket (+ repo, states, relations), User.client et
  User.allowedProjects, NotificationService, ProjectAllowedExtension, le bloc
  ROLE_CLIENT de MailAccessChecker
- front : pages /portal, layout portal, composants client-ticket/,
  AdminClientTicketTab, services/dto/i18n/docs associés
- fixtures : retire les users client-liot / client-acme
- migration Version20260522110000 (drop client_ticket, user_allowed_projects,
  colonnes liées ; task_document.task_id -> NOT NULL)
- tests : retire les cas obsolètes testant le blocage des clients sur le mail

Module gestion des absences (WIP) :
- entités / migrations (Version20260521160000, Version20260522090000)
- pages absences.vue / team-absences.vue, composants frontend/components/absence/
- services front, AccrueLeaveCommand, PublicHolidayController

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

migrations/Version20260522090000.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DoctrineMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+/**
+ * Absence management: split the paid-leave balance into "acquired" (Congés N-1,
+ * finalized and available) and "acquiring" (Congés N, "en cours d'acquisition"),
+ * mirroring the two columns on a French payslip.
+ *
+ * Existing paid-leave balances were filled solely by the monthly accrual, which
+ * credited `acquired`; those days actually belong to the current period's
+ * "en cours d'acquisition", so they are moved to `acquiring` on the way up.
+ */
+final class Version20260522090000 extends AbstractMigration
+{
+    public function getDescription(): string
+    {
+        return 'Add acquiring (en cours d\'acquisition) to absence_balance and reclassify existing paid-leave days';
+    }
+
+    public function up(Schema $schema): void
+    {
+        $this->addSql('ALTER TABLE absence_balance ADD acquiring DOUBLE PRECISION DEFAULT 0 NOT NULL');
+        $this->addSql("UPDATE absence_balance SET acquiring = acquired, acquired = 0 WHERE type = 'cp'");
+        $this->addSql('ALTER TABLE absence_balance ALTER acquiring DROP DEFAULT');
+    }
+
+    public function down(Schema $schema): void
+    {
+        // Fold the in-progress days back into acquired before dropping the column.
+        $this->addSql("UPDATE absence_balance SET acquired = acquired + acquiring WHERE type = 'cp'");
+        $this->addSql('ALTER TABLE absence_balance DROP acquiring');
+    }
+}