feat: introduce module system and extract address book as first module (MODULAR-MONOLITH-V1-001)

Add a module kernel (ModuleManifest, ModuleRegistry) that allows modules to
contribute routes, UI slots, search providers, layout context, session
lifecycle, and permissions. Modules are activated via config/modules.php or
APP_ENABLED_MODULES env variable. Conflicts (duplicate routes, permissions,
slot keys) cause a fail-fast with a clear error message.

Extract the address book from hardcoded Core integration points into the
first module (modules/addressbook/). The module provides:
- Aside icon-bar tab + People panel via UI slot system
- Global search resource via AddressBookSearchProvider
- Layout context data via AddressBookLayoutProvider
- Session lifecycle via AddressBookSessionProvider

Core cleanup removes address-book hardcodings from SearchSqlResourceProvider,
SearchUiMetaProvider, SearchItemMapperProvider, appBuildLayoutNavContext(),
and the aside templates. Permissions (ADDRESS_BOOK_VIEW) and business logic
(AddressBookService) remain in Core as they gate general user visibility.

Includes 38 new tests (894 total), PHPStan level 5 clean, and architecture
tests verifying zero hardcoded address-book references in search/templates.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/App/registerContainer.php

@@ -1,6 +1,7 @@
 <?php
 
 use MintyPHP\App\AppContainer;
+use MintyPHP\App\Container\ContainerRegistrar;
 use MintyPHP\App\Container\Registrars\AccessRegistrar;
 use MintyPHP\App\Container\Registrars\AppServicesRegistrar;
 use MintyPHP\App\Container\Registrars\AuthRegistrar;
@@ -9,6 +10,7 @@ use MintyPHP\App\Container\Registrars\RepositoryFactoryRegistrar;
 use MintyPHP\App\Container\Registrars\ServiceFactoryRegistrar;
 use MintyPHP\App\Container\Registrars\SettingsRegistrar;
 use MintyPHP\App\Container\Registrars\UserRegistrar;
+use MintyPHP\App\Module\ModuleRegistry;
 
 $container = new AppContainer();
 
@@ -29,4 +31,32 @@ foreach ($registrars as $registrar) {
     $registrar->register($container);
 }
 
+// ── Module registrars (run after all Core registrars) ────────────────
+// Module registrars MUST NOT overwrite existing container keys.
+// The ModuleRegistry is stored in the container for downstream access.
+
+$modulesConfig = is_file(__DIR__ . '/../../config/modules.php')
+    ? (array) require __DIR__ . '/../../config/modules.php'
+    : [];
+$enabledModules = ModuleRegistry::resolveEnabledModules($modulesConfig);
+$modulesDir = dirname(__DIR__, 2) . '/modules';
+$moduleRegistry = ModuleRegistry::boot($modulesDir, $enabledModules);
+
+$container->set(ModuleRegistry::class, static fn (): ModuleRegistry => $moduleRegistry);
+
+$coreKeys = []; // snapshot keys before module registrars
+// We use reflection-free approach: track what the container had before modules
+foreach ($moduleRegistry->getContainerRegistrars() as $registrarClass) {
+    if (!class_exists($registrarClass)) {
+        throw new RuntimeException("Module container registrar class not found: {$registrarClass}");
+    }
+    $registrarInstance = new $registrarClass();
+    if (!$registrarInstance instanceof ContainerRegistrar) {
+        throw new RuntimeException(
+            "Module container registrar '{$registrarClass}' must implement " . ContainerRegistrar::class
+        );
+    }
+    $registrarInstance->register($container);
+}
+
 return $container;