chore: add php-cs-fixer with PSR-12 config and CI check

- Add friendsofphp/php-cs-fixer to require-dev
- Create .php-cs-fixer.dist.php configured for @PSR12 ruleset
- Add php-cs-fixer dry-run step to CI pipeline
- Auto-fix existing PSR-12 violations
- Document code style tooling in readme.md

tests/Support/TotpTestHelper.php

@@ -1,4 +1,5 @@
 <?php
+
 declare(strict_types=1);
 
 namespace App\Tests\Support;
@@ -17,7 +18,8 @@ use Symfony\Component\Cache\Adapter\ArrayAdapter;
  * Provides a deterministic TOTP fixture plus a frozen clock and ready-made
  * ConfigBag / cache-pool helpers for tests that exercise TOTP-dependent code.
  */
-trait TotpTestHelper {
+trait TotpTestHelper
+{
     /** well-known Base32 test secret (JBSWY3DPEHPK3PXP) */
     private const string TOTP_SECRET = 'JBSWY3DPEHPK3PXP';
 
@@ -25,30 +27,37 @@ trait TotpTestHelper {
     protected const string FROZEN_TIME = '2025-06-15 12:00:00';
 
     /** Frozen clock that always returns the same instant. */
-    private function frozenClock(): PsrClockInterface {
+    private function frozenClock(): PsrClockInterface
+    {
         $time = self::FROZEN_TIME;
-        return new class($time) implements PsrClockInterface {
-            public function __construct(private string $time) {}
-            public function now(): DateTimeImmutable {
+        return new class ($time) implements PsrClockInterface {
+            public function __construct(private string $time)
+            {
+            }
+            public function now(): DateTimeImmutable
+            {
                 return new DateTimeImmutable($this->time);
             }
         };
     }
 
     /** Provisioning URI built from the well-known secret + frozen clock. */
-    private function totpUri(): string {
+    private function totpUri(): string
+    {
         $totp = TOTP::createFromSecret(self::TOTP_SECRET, $this->frozenClock());
         $totp->setLabel('Test-TOTP');
         return $totp->getProvisioningUri();
     }
 
     /** The TOTP code that is valid at the frozen timestamp. */
-    private function validTotpCode(): string {
+    private function validTotpCode(): string
+    {
         return TOTP::createFromSecret(self::TOTP_SECRET, $this->frozenClock())->now();
     }
 
     /** A fresh in-memory cache pool suitable for wrapping in MonitorCacheKeys. */
-    private function emptyPool(): CacheItemPoolInterface {
+    private function emptyPool(): CacheItemPoolInterface
+    {
         return new ArrayAdapter();
     }
 
@@ -67,9 +76,15 @@ trait TotpTestHelper {
         $clock = $this->frozenClock();
         $utilities = $this->createUtilities($clock);
         return new ConfigBag(
-            $utilities, $clock,
-            $cookieTtl, $this->totpUri(), $ipTtl, $teapot,
-            $errorMessage, $teapotTitle, $tooManyTitle,
+            $utilities,
+            $clock,
+            $cookieTtl,
+            $this->totpUri(),
+            $ipTtl,
+            $teapot,
+            $errorMessage,
+            $teapotTitle,
+            $tooManyTitle,
         );
     }
 
@@ -77,7 +92,8 @@ trait TotpTestHelper {
      * Minimal Utilities stub that never triggers TOTP generation when
      * a non-empty totpUri is supplied to ConfigBag.
      */
-    private function createUtilities(?PsrClockInterface $clock = null): Utilities {
+    private function createUtilities(?PsrClockInterface $clock = null): Utilities
+    {
         $clock ??= $this->frozenClock();
         $cache = $this->createStub(CacheItemPoolInterface::class);
         $cache->method('hasItem')->willReturn(false);