feat(client-portal) : phase 1 foundations — ROLE_CLIENT hardening + ClientTicket (back)

LST-69 (3.2) phase 1. New ClientPortal module + security foundations for the
client portal (spec docs/superpowers/specs/2026-03-15-client-portal-design.md).

- Security: User::getRoles() no longer adds ROLE_USER to ROLE_CLIENT users;
  role_hierarchy ROLE_ADMIN: [ROLE_USER, ROLE_CLIENT]. Existing Task/Project/
  Client/TimeEntry/metadata endpoints already required ROLE_USER -> a pure
  ROLE_CLIENT is walled off (verified: 403).
- User (Core): client (ManyToOne ClientInterface, SET NULL) + allowedProjects
  (ManyToMany ProjectInterface). UserInterface extended (getClient/
  getAllowedProjects).
- New ClientTicket entity (module ClientPortal) + enums + repository + API with
  per-client isolation (ClientTicketProvider: own tickets ∩ allowedProjects),
  per-project numbering under advisory lock (rejects if user.client null),
  status transition rules. ClientTicketInterface contract for Task/TaskDocument.
- TaskDocument generalized: task nullable + clientTicket (CASCADE) + CHECK;
  per-role access. Task.clientTicket exposed in task:read.
- Additive migration; demo client fixtures.
- Tenancy tests assert the isolation invariant (a client never sees another
  client's tickets) rather than brittle absolute counts (shared test DB).

178 tests green, mapping valid, cs-fixer clean.

src/Shared/Domain/Contract/UserInterface.php

@@ -4,6 +4,8 @@ declare(strict_types=1);
 
 namespace App\Shared\Domain\Contract;
 
+use Doctrine\Common\Collections\Collection;
+
 /**
  * Contrat de LECTURE de l'identité, consommé hors du module Core.
  * Les écritures (setPassword, setters HR…) restent sur le concret Core\Domain\Entity\User.
@@ -29,4 +31,16 @@ interface UserInterface
 
     /** @return list<string> */
     public function getEffectivePermissions(): array;
+
+    /**
+     * Client this user belongs to, or null for an internal user.
+     */
+    public function getClient(): ?ClientInterface;
+
+    /**
+     * Projects a client user is allowed to access.
+     *
+     * @return Collection<int, ProjectInterface>
+     */
+    public function getAllowedProjects(): Collection;
 }