Feature: Implement secure public pre-registration flow with CAPTCHA and HTMX dashboard

- Created V16 Flyway migration for pre_inscription and token_pre_inscription tables.
- Added PreInscription and TokenPreInscription entities with respective repositories.
- Updated SecurityConfig to allow public access to /inscription-public/**.
- Implemented CaptchaValidationService to interact with Cloudflare Turnstile API.
- Created PublicInscriptionController for managing the QR code entry, CAPTCHA validation, ephemeral tokens, and public form submission.
- Added public Thymeleaf views (demarrer, formulaire, succes, lien-expire) with TailwindCSS.
- Developed AdminPreInscriptionController and PreInscriptionService to handle back-office validation and rejection workflows.
- Built the admin pre-inscriptions dashboard list view.
- Added a dynamic, polling notification badge in the sidebar using HTMX, auto-updating on validation/rejection events.

as-talange-web/src/main/resources/templates/fragments/sidebar.html

@@ -12,6 +12,10 @@
             <a href="/" th:classappend="${requestURI == '/' ? 'bg-blue-50 text-blue-700 font-medium' : 'text-gray-600 hover:bg-gray-50 hover:text-gray-900'}" class="block px-3 py-2 rounded-lg transition-colors">Tableau de bord</a>
             <a href="/adherents" th:classappend="${requestURI != null and requestURI.startsWith('/adherents') ? 'bg-blue-50 text-blue-700 font-medium' : 'text-gray-600 hover:bg-gray-50 hover:text-gray-900'}" class="block px-3 py-2 rounded-lg transition-colors">Adhérents</a>
             
+            <a sec:authorize="hasAnyRole('ROLE_ADMIN', 'ROLE_AGENT_SAISIE')" href="/admin/pre-inscriptions" th:classappend="${requestURI != null and requestURI.startsWith('/admin/pre-inscriptions') ? 'bg-blue-50 text-blue-700 font-medium' : 'text-gray-600 hover:bg-gray-50 hover:text-gray-900'}" class="flex items-center px-3 py-2 rounded-lg transition-colors">
+                <span>Pré-inscriptions</span>
+                <span hx-get="/admin/pre-inscriptions/count" hx-trigger="every 30s, refreshBadge from:body" hx-swap="outerHTML"></span>
+            </a>
             <a sec:authorize="hasAnyRole('ROLE_ADMIN', 'ROLE_TRESORERIE')" href="/paiements" th:classappend="${requestURI != null and requestURI.startsWith('/paiements') ? 'bg-blue-50 text-blue-700 font-medium' : 'text-gray-600 hover:bg-gray-50 hover:text-gray-900'}" class="block px-3 py-2 rounded-lg transition-colors">Paiements</a>
             
             <th:block sec:authorize="hasAnyRole('ROLE_ADMIN', 'ROLE_AGENT_SAISIE')">