Upgrade to PHPUnit 10, add PHPCS with WPCS compliance, add phpcs CI job

- Upgrade PHPUnit 9.6 → 10, update phpunit.xml.dist schema
- Add PHPCS 3.13 with WordPress-Extra + PHPCompatibilityWP standards
- PHPCBF auto-fix + manual fixes for full WPCS compliance
- Add phpcs job to release workflow (parallel with lint)
- Pin composer platform to PHP 8.3 to prevent incompatible dep locks

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -28,7 +28,30 @@ jobs:
           find includes -name "*.php" -print0 | xargs -0 -n1 php -l
           find tests -name "*.php" -print0 | xargs -0 -n1 php -l
 
+  phpcs:
+    name: PHP CodeSniffer
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.3'
+          extensions: mbstring, xml
+          tools: composer:v2
+
+      - name: Install Composer dependencies
+        run: |
+          composer config platform.php 8.3.0
+          composer install --optimize-autoloader --no-interaction
+
+      - name: Run PHPCS
+        run: vendor/bin/phpcs
+
   test:
+    name: PHP Unit
     runs-on: ubuntu-latest
     needs: lint
     steps:
@@ -51,7 +74,7 @@ jobs:
         run: vendor/bin/phpunit --testdox
 
   build-release:
-    needs: test
+    needs: [test, phpcs]
     runs-on: ubuntu-latest
     steps:
       - name: Checkout code