feat(mail) : migrate Mail integration into module (back)

LST-67 (2.5) backend. Behaviour-preserving move of the IMAP mail integration
into src/Module/Mail/. All /api/mail/* routes, securities (ROLE_CLIENT still
excluded via MailAccessChecker) and the async sync are unchanged.

- 4 entities + 4 repositories (Domain interfaces + Doctrine impls, bound).
  TaskMailLink.task now references TaskInterface (contract) instead of the
  concrete PM Task. Link/unlink/list-mails controllers load tasks via
  TaskRepositoryInterface; MailCreateTaskController keeps the concrete Task
  (instantiation) — documented Mail->PM coupling.
- Domain (MailProviderInterface, exception), Application (5 DTOs, MailSyncService,
  MailSyncRequested message + handler), Infrastructure (ImapMailProvider +
  MimeHeaderDecoder, MailAccessChecker, 2 console commands, 12 controllers,
  ApiPlatform state + MailSettings resource). TokenEncryptor stays shared.
- doctrine mapping Mail; messenger routing repointed; services.yaml repo +
  provider bindings; MailModule registered (id mail, mail.access/configure).
- #[Auditable] + Timestampable on MailConfiguration only (additive migration);
  IMAP data entities keep their own sync timestamps.

163 tests green, mapping valid, no route regression, cs-fixer clean.

src/Module/Mail/Domain/Repository/MailConfigurationRepositoryInterface.php

@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Module\Mail\Domain\Repository;
+
+use App\Module\Mail\Domain\Entity\MailConfiguration;
+
+interface MailConfigurationRepositoryInterface
+{
+    public function findSingleton(): ?MailConfiguration;
+}

src/Module/Mail/Domain/Repository/MailFolderRepositoryInterface.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Module\Mail\Domain\Repository;
+
+use App\Module\Mail\Domain\Entity\MailFolder;
+
+interface MailFolderRepositoryInterface
+{
+    /**
+     * @return list<MailFolder>
+     */
+    public function findAllOrderedByPath(): array;
+
+    public function findByPath(string $path): ?MailFolder;
+}

src/Module/Mail/Domain/Repository/MailMessageRepositoryInterface.php

@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Module\Mail\Domain\Repository;
+
+use App\Module\Mail\Domain\Entity\MailFolder;
+use App\Module\Mail\Domain\Entity\MailMessage;
+
+interface MailMessageRepositoryInterface
+{
+    public function findById(int $id): ?MailMessage;
+
+    /**
+     * @return list<MailMessage>
+     */
+    public function findAll(): array;
+
+    public function findByMessageId(string $messageId): ?MailMessage;
+
+    public function findByFolderAndUid(MailFolder $folder, int $uid): ?MailMessage;
+
+    /**
+     * @return list<MailMessage>
+     */
+    public function findByFolderPaginated(MailFolder $folder, int $limit, int $offset): array;
+
+    public function countUnreadByFolder(MailFolder $folder): int;
+
+    public function findMaxUidInFolder(MailFolder $folder): int;
+
+    /**
+     * @return list<MailMessage>
+     */
+    public function findLastNByFolder(MailFolder $folder, int $limit): array;
+
+    /**
+     * @return list<int>
+     */
+    public function findAllUidsByFolder(MailFolder $folder): array;
+
+    /**
+     * Pagination cursor : retourne $limit messages apres le cursor (sentAt DESC, id DESC).
+     * Cursor format : base64url(sentAt_iso8601:id) - null pour la premiere page.
+     *
+     * @return array{messages: list<MailMessage>, nextCursor: ?string}
+     */
+    public function findByFolderCursor(MailFolder $folder, int $limit, ?string $cursor): array;
+}

src/Module/Mail/Domain/Repository/TaskMailLinkRepositoryInterface.php

@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Module\Mail\Domain\Repository;
+
+use App\Module\Mail\Domain\Entity\MailMessage;
+use App\Module\Mail\Domain\Entity\TaskMailLink;
+use App\Shared\Domain\Contract\TaskInterface;
+
+interface TaskMailLinkRepositoryInterface
+{
+    /**
+     * @return list<TaskMailLink>
+     */
+    public function findByTask(TaskInterface $task): array;
+
+    public function findByTaskAndMessage(TaskInterface $task, MailMessage $message): ?TaskMailLink;
+
+    /**
+     * @return list<TaskMailLink>
+     */
+    public function findByMessage(MailMessage $message): array;
+}