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>

tests/App/Module/ModuleManifestTest.php

@@ -0,0 +1,72 @@
+<?php
+
+namespace MintyPHP\Tests\App\Module;
+
+use InvalidArgumentException;
+use MintyPHP\App\Module\ModuleManifest;
+use PHPUnit\Framework\TestCase;
+
+final class ModuleManifestTest extends TestCase
+{
+    public function testMinimalManifest(): void
+    {
+        $manifest = ModuleManifest::fromArray(['id' => 'testmod'], '/tmp/modules/testmod');
+
+        self::assertSame('testmod', $manifest->id);
+        self::assertSame('0.0.0', $manifest->version);
+        self::assertFalse($manifest->enabledByDefault);
+        self::assertSame(100, $manifest->loadOrder);
+        self::assertSame([], $manifest->routes);
+        self::assertSame([], $manifest->permissions);
+        self::assertSame([], $manifest->searchResources);
+        self::assertNull($manifest->migrationsPath);
+    }
+
+    public function testFullManifest(): void
+    {
+        $raw = [
+            'id' => 'addressbook',
+            'version' => '1.0.0',
+            'enabled_by_default' => true,
+            'load_order' => 10,
+            'routes' => [['path' => '/address-book', 'target' => 'address-book/index']],
+            'public_paths' => [],
+            'container_registrars' => ['App\\Registrar'],
+            'ui_slots' => ['aside.tab_panel' => [['key' => 'people', 'label' => 'People']]],
+            'search_resources' => ['App\\SearchProvider'],
+            'asset_groups' => ['address-book' => ['css/view.css']],
+            'scheduler_jobs' => [],
+            'layout_context_providers' => ['App\\LayoutProvider'],
+            'session_providers' => ['App\\SessionProvider'],
+            'permissions' => ['address_book.view'],
+            'migrations_path' => 'db/updates',
+        ];
+
+        $manifest = ModuleManifest::fromArray($raw, '/srv/modules/addressbook');
+
+        self::assertSame('addressbook', $manifest->id);
+        self::assertSame('1.0.0', $manifest->version);
+        self::assertTrue($manifest->enabledByDefault);
+        self::assertSame(10, $manifest->loadOrder);
+        self::assertCount(1, $manifest->routes);
+        self::assertSame(['address_book.view'], $manifest->permissions);
+        self::assertSame('/srv/modules/addressbook/db/updates', $manifest->migrationsPath);
+        self::assertSame(['App\\LayoutProvider'], $manifest->layoutContextProviders);
+        self::assertSame(['App\\SessionProvider'], $manifest->sessionProviders);
+    }
+
+    public function testMissingIdThrows(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage('non-empty string "id"');
+
+        ModuleManifest::fromArray([], '/tmp/modules/broken');
+    }
+
+    public function testEmptyIdThrows(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+
+        ModuleManifest::fromArray(['id' => '  '], '/tmp/modules/broken');
+    }
+}