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>

tests/Feature/Database/FoundationMigrationsTest.php

@@ -0,0 +1,11 @@
+<?php
+
+use Illuminate\Support\Facades\Schema;
+
+test('workspace_user table has permissions column', function () {
+    expect(Schema::hasColumn('workspace_user', 'permissions'))->toBeTrue();
+});
+
+test('declarations table has archived_at column', function () {
+    expect(Schema::hasColumn('declarations', 'archived_at'))->toBeTrue();
+});