feat(absence) : migrate Absence domain into module (back)

LST-66 (2.3) backend. Behaviour-preserving move of the absences domain into
src/Module/Absence/. API operations, securities, routes and the 10 MCP tool
names are unchanged.

- 3 entities + 3 enums moved to Domain/{Entity,Enum}; user relations stay on
  UserInterface. 3 repositories split into Domain/Repository interfaces +
  Doctrine impls (bound in services.yaml); find() kept off interfaces
  (findById instead).
- Pure services (AbsenceDayCalculator, PublicHolidayProvider) -> Domain/Service;
  AbsenceBalanceService -> Application/Service; State (5), controllers (5),
  10 MCP tools and AccrueLeaveCommand -> Infrastructure/.
- New LeaveProfileInterface contract (Shared) exposes the HR getters used by
  AbsenceBalanceService/AccrueLeaveCommand; User implements it -> Absence no
  longer imports the concrete Core User. MCP tools/command inject
  UserRepositoryInterface (findById) instead of the concrete repository.
- Timestampable/Blamable added to AbsenceBalance and AbsencePolicy (additive
  migration: created_at/updated_at + created_by/updated_by FK ON DELETE SET
  NULL + COMMENT). AbsenceRequest untouched (already has createdAt/reviewedAt).
- AbsenceModule registered (id absence, 4 RBAC perms, not re-wired); doctrine
  mapping added; team-absences sidebar item gated by the module.

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

config/sidebar.php

@@ -30,7 +30,7 @@ return [
         'icon'  => 'mdi:cog-outline',
         'roles' => ['ROLE_ADMIN'],
         'items' => [
-            ['label' => 'sidebar.admin.teamAbsences', 'to' => '/team-absences', 'icon' => 'mdi:calendar-account-outline'],
+            ['label' => 'sidebar.admin.teamAbsences', 'to' => '/team-absences', 'icon' => 'mdi:calendar-account-outline', 'module' => 'absence'],
             ['label' => 'sidebar.admin.administration', 'to' => '/admin', 'icon' => 'mdi:cog-outline', 'permission' => 'core.users.view'],
         ],
     ],