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>

resources/views/emails/declaration-text-message.blade.php

@@ -0,0 +1,13 @@
+<x-mail::message>
+# Nouveau message
+
+Bonjour,
+
+Vous avez reçu un nouveau message pour le dossier **{{ $declarationTitle }}**.
+
+> {{ $body }}
+
+<x-mail::button :url="$messagesUrl" color="primary">
+Voir les messages
+</x-mail::button>
+</x-mail::message>