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

config/sanctum.php

@@ -1,5 +1,10 @@
 <?php
 
+declare(strict_types=1);
+
+use Illuminate\Cookie\Middleware\EncryptCookies;
+use Illuminate\Foundation\Http\Middleware\ValidateCsrfToken;
+use Laravel\Sanctum\Http\Middleware\AuthenticateSession;
 use Laravel\Sanctum\Sanctum;
 
 return [
@@ -15,7 +20,7 @@ return [
     |
     */
 
-    'stateful' => explode(',', env('SANCTUM_STATEFUL_DOMAINS', sprintf(
+    'stateful' => explode(',', (string) env('SANCTUM_STATEFUL_DOMAINS', sprintf(
         '%s%s',
         'localhost,localhost:3000,127.0.0.1,127.0.0.1:8000,::1',
         Sanctum::currentApplicationUrlWithPort(),
@@ -76,9 +81,9 @@ return [
     */
 
     'middleware' => [
-        'authenticate_session' => Laravel\Sanctum\Http\Middleware\AuthenticateSession::class,
-        'encrypt_cookies' => Illuminate\Cookie\Middleware\EncryptCookies::class,
-        'validate_csrf_token' => Illuminate\Foundation\Http\Middleware\ValidateCsrfToken::class,
+        'authenticate_session' => AuthenticateSession::class,
+        'encrypt_cookies' => EncryptCookies::class,
+        'validate_csrf_token' => ValidateCsrfToken::class,
     ],
 
 ];