test: add 92 tests for 12 untested gateway and service classes

Cover Settings gateways (Session, LoginPersistence, SystemAudit, Smtp,
FrontendTelemetry, Metadata, App), Auth gateways (ExternalIdentity,
Tenant), DirectorySettings, UserSettings, and HotkeyService.
Gateway test coverage rises from 25% to 52%, overall service/gateway
coverage from 58.6% to 70.7%.

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

tests/Service/Ui/HotkeyServiceTest.php

@@ -0,0 +1,83 @@
+<?php
+
+namespace MintyPHP\Tests\Service\Ui;
+
+use MintyPHP\Service\Ui\HotkeyService;
+use PHPUnit\Framework\TestCase;
+
+class HotkeyServiceTest extends TestCase
+{
+    public function testListReturnsNonEmptyArray(): void
+    {
+        $result = HotkeyService::list();
+
+        $this->assertIsArray($result);
+        $this->assertNotEmpty($result);
+    }
+
+    public function testListEntriesHaveRequiredKeys(): void
+    {
+        $result = HotkeyService::list();
+
+        foreach ($result as $index => $entry) {
+            $this->assertArrayHasKey('action_key', $entry, "Entry #{$index} is missing 'action_key'");
+            $this->assertArrayHasKey('mac', $entry, "Entry #{$index} is missing 'mac'");
+            $this->assertArrayHasKey('win', $entry, "Entry #{$index} is missing 'win'");
+            $this->assertNotEmpty($entry['action_key'], "Entry #{$index} has empty 'action_key'");
+            $this->assertNotEmpty($entry['mac'], "Entry #{$index} has empty 'mac'");
+            $this->assertNotEmpty($entry['win'], "Entry #{$index} has empty 'win'");
+        }
+    }
+
+    public function testListEntriesHaveExactlyThreeKeys(): void
+    {
+        $result = HotkeyService::list();
+
+        foreach ($result as $index => $entry) {
+            $this->assertCount(3, $entry, "Entry #{$index} should have exactly 3 keys");
+        }
+    }
+
+    public function testSearchKeywordsReturnsNonEmptyArray(): void
+    {
+        $result = HotkeyService::searchKeywords();
+
+        $this->assertIsArray($result);
+        $this->assertNotEmpty($result);
+    }
+
+    public function testSearchKeywordsContainsExpectedTerms(): void
+    {
+        $result = HotkeyService::searchKeywords();
+
+        $this->assertContains('hotkey', $result);
+        $this->assertContains('shortcut', $result);
+        $this->assertContains('keyboard', $result);
+    }
+
+    public function testSearchKeywordsAreAllStrings(): void
+    {
+        $result = HotkeyService::searchKeywords();
+
+        foreach ($result as $keyword) {
+            $this->assertIsString($keyword);
+            $this->assertNotEmpty($keyword);
+        }
+    }
+
+    public function testListReturnsDeterministicResult(): void
+    {
+        $first = HotkeyService::list();
+        $second = HotkeyService::list();
+
+        $this->assertSame($first, $second);
+    }
+
+    public function testSearchKeywordsReturnsDeterministicResult(): void
+    {
+        $first = HotkeyService::searchKeywords();
+        $second = HotkeyService::searchKeywords();
+
+        $this->assertSame($first, $second);
+    }
+}