feat: add LDAP authentication as per-tenant login method

Add LDAP as a third authentication option alongside local password and
Microsoft Entra ID SSO. Per-tenant configuration supports Active Directory,
OpenLDAP, and FreeIPA with configurable attribute mapping, search-then-bind
and direct-bind methods, encrypted bind credentials (AES-256-GCM),
profile sync on login, and user auto-provisioning via external identity
linking.

Includes admin UI for connection settings with test-connection button,
login page LDAP form, 25 new PHPUnit tests, and de/en translations.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/Repository/Tenant/TenantLdapAuthRepositoryInterface.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace MintyPHP\Repository\Tenant;
+
+/** Contract for storing and retrieving LDAP authentication configuration per tenant. */
+interface TenantLdapAuthRepositoryInterface
+{
+    public function findByTenantId(int $tenantId): ?array;
+
+    public function listByTenantIds(array $tenantIds): array;
+
+    public function upsertByTenantId(int $tenantId, array $data): bool;
+}