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/Unit/Trait/StringTraitTest.php

@@ -1,4 +1,5 @@
 <?php
+
 declare(strict_types=1);
 
 namespace App\Tests\Unit\Trait;
@@ -6,30 +7,36 @@ namespace App\Tests\Unit\Trait;
 use App\Trait\StringTrait;
 use PHPUnit\Framework\TestCase;
 
-final class StringTraitTest extends TestCase {
+final class StringTraitTest extends TestCase
+{
     use StringTrait;
 
-    public function testMakeCacheKeySanitizesInvalidChars(): void {
+    public function testMakeCacheKeySanitizesInvalidChars(): void
+    {
         self::assertSame('hello_world', $this->makeCacheKey('hello world'));
         self::assertSame('hello_world', $this->makeCacheKey('hello!world'));
         self::assertSame('a_b_c_d', $this->makeCacheKey('a/b@c#d'));
     }
 
-    public function testMakeCacheKeyPreservesValidChars(): void {
+    public function testMakeCacheKeyPreservesValidChars(): void
+    {
         self::assertSame('ABC_123.abc', $this->makeCacheKey('ABC_123.abc'));
     }
 
-    public function testMakeCacheKeyTruncatesLongNames(): void {
+    public function testMakeCacheKeyTruncatesLongNames(): void
+    {
         $long = str_repeat('a', 300);
         $result = $this->makeCacheKey($long);
         self::assertSame(128, mb_strlen($result));
     }
 
-    public function testMakeCacheKeyEmptyString(): void {
+    public function testMakeCacheKeyEmptyString(): void
+    {
         self::assertSame('', $this->makeCacheKey(''));
     }
 
-    public function testMakeCacheKeyWithOnlyInvalidChars(): void {
+    public function testMakeCacheKeyWithOnlyInvalidChars(): void
+    {
         // preg_replace with + collapses consecutive invalid chars into one _
         self::assertSame('_', $this->makeCacheKey('!!!'));
         self::assertSame('_', $this->makeCacheKey('   '));
@@ -37,7 +44,8 @@ final class StringTraitTest extends TestCase {
         self::assertSame('_', $this->makeCacheKey('!@ #'));
     }
 
-    public function testMakeCacheKeyTruncatesToExactly128(): void {
+    public function testMakeCacheKeyTruncatesToExactly128(): void
+    {
         $input = str_repeat('a', 128);
         self::assertSame(128, mb_strlen($this->makeCacheKey($input)));
         self::assertSame($input, $this->makeCacheKey($input));
@@ -46,14 +54,16 @@ final class StringTraitTest extends TestCase {
         self::assertSame(128, mb_strlen($this->makeCacheKey($input129)));
     }
 
-    public function testMakeCacheKeyWithMultibyteChars(): void {
+    public function testMakeCacheKeyWithMultibyteChars(): void
+    {
         // multibyte chars are replaced with a single underscore
         $result = $this->makeCacheKey('héllo wörld');
         // é and ö are not in [A-Za-z0-9_.] so they become _
         self::assertSame('h_llo_w_rld', $result);
     }
 
-    public function testMakeCacheKeyWithEmoji(): void {
+    public function testMakeCacheKeyWithEmoji(): void
+    {
         $result = $this->makeCacheKey('a🎉b');
         self::assertSame('a_b', $result);
     }