Add unit tests for models and services

- Implemented unit tests for the Package model, covering methods such as generateId, findById, findByName, and version management.
- Created unit tests for the Repository model, including repository creation, name validation, and retrieval methods.
- Added tests for the Session model, focusing on session creation, validation, and invalidation.
- Developed unit tests for the User model, ensuring user creation, password hashing, and retrieval methods function correctly.
- Implemented AuthService tests, validating login, token refresh, and session management.
- Added TokenService tests, covering token creation, validation, and revocation processes.

test/fixtures/composer/stacktest/demo-package/src/Demo.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace StackTest\DemoPackage;
+
+/**
+ * Demo class for Stack.Gallery Registry e2e tests.
+ */
+class Demo
+{
+    /**
+     * Greet the given name.
+     *
+     * @param string $name The name to greet
+     * @return string A greeting message
+     */
+    public static function greet(string $name): string
+    {
+        return "Hello, {$name}!";
+    }
+}