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/Enums/DeclarationStatus.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace App\Enums;
+
+use BenSampo\Enum\Enum;
+
+final class DeclarationStatus extends Enum
+{
+    const Created = 'created';
+
+    const EnCours = 'en_cours';
+
+    const EnAttenteClient = 'en_attente_client';
+
+    const Termine = 'termine';
+
+    const Ferme = 'ferme';
+
+    /**
+     * Get French display labels for each status.
+     *
+     * @return array<string, string>
+     */
+    public static function labels(): array
+    {
+        return [
+            self::Created => 'Créé',
+            self::EnCours => 'En cours',
+            self::EnAttenteClient => 'En attente client',
+            self::Termine => 'Terminé',
+            self::Ferme => 'Fermé',
+        ];
+    }
+
+    /**
+     * Get the valid next statuses for each status per the architecture status flow.
+     *
+     * @return array<string, list<string>>
+     */
+    public static function allowedTransitions(): array
+    {
+        return [
+            self::Created => [self::EnCours],
+            self::EnCours => [self::EnAttenteClient, self::Termine],
+            self::EnAttenteClient => [self::EnCours],
+            self::Termine => [self::Ferme],
+            self::Ferme => [],
+        ];
+    }
+}