refactor: rename lib/ to core/ for clearer core-module separation

Rename the top-level lib/ directory to core/ so the project root
immediately communicates which code is core platform and which lives
in modules/. PHP namespaces (MintyPHP\*) are unchanged — only the
Composer PSR-4 path mapping moves from lib/ to core/.

Module-internal lib/ directories (modules/*/lib/) are untouched.

Updated across the full stack:
- composer.json PSR-4 mapping
- bootstrap entry points (web/index.php, bin/*, tests/bootstrap.php)
- tooling configs (phpstan.neon, phpunit.xml, php-cs-fixer)
- 26 architecture contract tests
- enforcement-policy, guard-catalog, quality-gates
- all documentation (CLAUDE.md, README, 25 docs/, .agents/skills/)
- bin/qa-extended.sh search paths
- .claude/settings.local.json permission paths

Workflow: .agents/runs/CORE-LIB-RENAME-001/ (Analyst → Planner →
Executor → Code Review (4 findings fixed) → Security Review →
Acceptance Test → Finalizer)

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

core/Service/User/UserSettingsGateway.php

@@ -0,0 +1,65 @@
+<?php
+
+namespace MintyPHP\Service\User;
+
+use MintyPHP\Service\Settings\SettingsAppGateway;
+use MintyPHP\Service\Settings\SettingsDefaultsGateway;
+use MintyPHP\Service\Settings\SettingsUserLifecycleGateway;
+
+class UserSettingsGateway
+{
+    public function __construct(
+        private readonly SettingsDefaultsGateway $settingsDefaultsGateway,
+        private readonly SettingsAppGateway $settingsAppGateway,
+        private readonly SettingsUserLifecycleGateway $settingsUserLifecycleGateway
+    ) {
+    }
+
+    public function getDefaultTenantId(): ?int
+    {
+        return $this->settingsDefaultsGateway->getDefaultTenantId();
+    }
+
+    public function getDefaultRoleId(): ?int
+    {
+        return $this->settingsDefaultsGateway->getDefaultRoleId();
+    }
+
+    public function getDefaultDepartmentId(): ?int
+    {
+        return $this->settingsDefaultsGateway->getDefaultDepartmentId();
+    }
+
+    public function getAppTheme(): ?string
+    {
+        return $this->settingsAppGateway->getAppTheme();
+    }
+
+    /**
+     * @return array<string, string>
+     */
+    public function appThemes(): array
+    {
+        return $this->settingsAppGateway->listThemes();
+    }
+
+    public function defaultTheme(): string
+    {
+        return $this->settingsAppGateway->resolveDefaultTheme();
+    }
+
+    public function normalizeTheme(?string $theme): string
+    {
+        return $this->settingsAppGateway->normalizeTheme($theme);
+    }
+
+    public function getUserInactivityDeactivateDays(): int
+    {
+        return $this->settingsUserLifecycleGateway->getUserInactivityDeactivateDays();
+    }
+
+    public function getUserInactivityDeleteDays(): int
+    {
+        return $this->settingsUserLifecycleGateway->getUserInactivityDeleteDays();
+    }
+}