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.

config/packages/doctrine.yaml

@@ -58,6 +58,11 @@ doctrine:
                 is_bundle: false
                 dir: '%kernel.project_dir%/src/Module/Directory/Domain/Entity'
                 prefix: 'App\Module\Directory\Domain\Entity'
+            Mail:
+                type: attribute
+                is_bundle: false
+                dir: '%kernel.project_dir%/src/Module/Mail/Domain/Entity'
+                prefix: 'App\Module\Mail\Domain\Entity'
         controller_resolver:
             auto_mapping: false
 

config/packages/messenger.yaml

@@ -23,7 +23,7 @@ framework:
             # messenger:consume à maintenir. La sync de fond reste assurée par le cron OS
             # (app:mail:sync, synchrone, indépendant du bus). Repasser à `async` + worker si
             # la boîte grossit au point que la sync à la demande approche le timeout PHP.
-            'App\Message\MailSyncRequested': sync
+            'App\Module\Mail\Application\Message\MailSyncRequested': sync
 
 when@test:
     framework: