feat: complete Epic 0 — foundation migration & infrastructure setup

Stories 0.2-0.5: rename folders→declarations (backend+frontend), configure
Redis for cache/queue/sessions, add foundation database migrations
(permissions, archived_at), replace DeclarationStatus enum with architecture
lifecycle values, create DeclarationObserver for status transition validation
and auto-archive, fix controller status transitions to respect observer rules.

93 tests pass (240 assertions).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Http/Middleware/ValidateClientPortalToken.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace App\Http\Middleware;
+
+use App\Models\DeclarationInvitation;
+use Closure;
+use Illuminate\Http\Request;
+use Symfony\Component\HttpFoundation\Response;
+
+class ValidateClientPortalToken
+{
+    /**
+     * Handle an incoming request.
+     *
+     * @param  \Closure(\Illuminate\Http\Request): (\Symfony\Component\HttpFoundation\Response)  $next
+     */
+    public function handle(Request $request, Closure $next): Response
+    {
+        $token = $request->route('token');
+
+        $invitation = DeclarationInvitation::query()
+            ->where('token', $token)
+            ->with(['declaration.client', 'declaration.assignee', 'declaration.creator'])
+            ->first();
+
+        if (! $invitation || ! $invitation->isValid()) {
+            abort(404, 'Lien invalide ou expiré.');
+        }
+
+        $request->attributes->set('declaration_invitation', $invitation);
+
+        return $next($request);
+    }
+}