feat(integration) : migrate Gitea/BookStack/Zimbra/Share into module (back)

LST-68 (2.6) backend. Behaviour-preserving move of the external integrations
into src/Module/Integration/. All 26 routes and securities unchanged.

- 5 entities (4 *Configuration singletons + TaskBookStackLink) + 5 repositories
  (Domain interfaces + Doctrine impls, bound). TaskBookStackLink.task now
  references TaskInterface (contract).
- Domain (FileSource interface, SharePathResolver, share DTOs + exceptions);
  Infrastructure (GiteaApiService, BookStackApiService, SmbFileSource, 15
  ApiResources, 21 State, 4 Share controllers).
- Cross-module couplings via abstractions: CalDavService (PM) injects
  ZimbraConfigurationRepositoryInterface; PM TaskDocument consumers repointed
  to the module's FileSource/SharePathResolver; Gitea/BookStack State load
  tasks via TaskRepositoryInterface (concrete Project read for integration
  fields — documented). ZimbraTestConnection keeps CalDavService (no build
  cycle). TokenEncryptor stays shared.
- IntegrationModule registered; doctrine mapping added.
- #[Auditable] + Timestampable on the 4 Configuration entities (additive
  migration on the 4 *_configuration tables).

163 tests green, container compiles (no cycle), no route regression, cs-fixer clean.

config/modules.php

@@ -10,6 +10,7 @@ declare(strict_types=1);
 use App\Module\Absence\AbsenceModule;
 use App\Module\Core\CoreModule;
 use App\Module\Directory\DirectoryModule;
+use App\Module\Integration\IntegrationModule;
 use App\Module\Mail\MailModule;
 use App\Module\ProjectManagement\ProjectManagementModule;
 use App\Module\TimeTracking\TimeTrackingModule;
@@ -21,4 +22,5 @@ return [
     AbsenceModule::class,
     DirectoryModule::class,
     MailModule::class,
+    IntegrationModule::class,
 ];