feat: integrate PHPStan, Rector and Pint code quality tools (#13)

* feat: integrate PHPStan, Rector and Pint code quality tools

- Add larastan, rector, and rector-laravel dev dependencies
- Configure PHPStan at max level with Larastan extension
- Configure Rector with Laravel sets and code quality rules
- Configure Pint with strict rules (final_class, strict_types)
- Add composer scripts: lint, test:lint, test:types, test:unit
- Add GitHub Actions workflow for CI on push/PR
- Apply code style fixes across all files

* docs: add code quality section to README

database/factories/UserFactory.php

@@ -1,20 +1,23 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Database\Factories;
 
+use App\Models\User;
 use Illuminate\Database\Eloquent\Factories\Factory;
 use Illuminate\Support\Facades\Hash;
 use Illuminate\Support\Str;
 
 /**
- * @extends \Illuminate\Database\Eloquent\Factories\Factory<\App\Models\User>
+ * @extends Factory<User>
  */
-class UserFactory extends Factory
+final class UserFactory extends Factory
 {
     /**
      * The current password being used by the factory.
      */
-    protected static ?string $password;
+    private static ?string $password = null;
 
     /**
      * Define the model's default state.
@@ -27,7 +30,7 @@ class UserFactory extends Factory
             'name' => fake()->name(),
             'email' => fake()->unique()->safeEmail(),
             'email_verified_at' => now(),
-            'password' => static::$password ??= Hash::make('password'),
+            'password' => self::$password ??= Hash::make('password'),
             'remember_token' => Str::random(10),
         ];
     }
@@ -37,7 +40,7 @@ class UserFactory extends Factory
      */
     public function unverified(): static
     {
-        return $this->state(fn (array $attributes) => [
+        return $this->state(fn (array $attributes): array => [
             'email_verified_at' => null,
         ]);
     }