Added mail to inform users about still running time entries

tests/Unit/Mail/TimeEntryStillRunningMailTest.php

@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Unit\Mail;
+
+use App\Mail\TimeEntryStillRunningMail;
+use App\Models\TimeEntry;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\UsesClass;
+use Tests\TestCaseWithDatabase;
+
+#[CoversClass(TimeEntryStillRunningMail::class)]
+#[UsesClass(TimeEntryStillRunningMail::class)]
+class TimeEntryStillRunningMailTest extends TestCaseWithDatabase
+{
+    public function test_mail_renders_content_correctly(): void
+    {
+        // Arrange
+        $user = $this->createUserWithPermission();
+        $timeEntry = TimeEntry::factory()->create([
+            'description' => 'TEST 123',
+        ]);
+        $mail = new TimeEntryStillRunningMail($timeEntry, $user->user);
+
+        // Act
+        $rendered = $mail->render();
+
+        // Assert
+        $this->assertStringContainsString('Your currently running time entry "TEST 123"', $rendered);
+    }
+}