ci: add automatic PHP CS Fixer workflow for PRs

Replace the dry-run CS check in build.yml with a dedicated workflow
that automatically runs php-cs-fixer and commits any fixes directly
to the PR branch via stefanzweifel/git-auto-commit-action.

This removes the burden from contributors who forget to run CS Fixer
locally, and ensures the correct PHP/CS Fixer version is always used
regardless of the contributor's local environment.

https://claude.ai/code/session_01WJEcEkXb8rGmmXPuF3nL95

Author: claude

.github/workflows/build.yml

@@ -42,10 +42,6 @@ jobs:
     - name: Install dependencies
       run: composer install --prefer-dist
 
-    - name: Coding Standard Checks
-      if: ${{ matrix.php-versions  == '8.0' }}
-      run: PHP_CS_FIXER_IGNORE_ENV=1 ./bin/php-cs-fixer fix --dry-run --diff
-
     - name: Static Analysis
       if: ${{ matrix.php-versions  == '8.0' }}
       run: ./bin/psalm.phar --no-cache

.github/workflows/cs-fixer.yml

@@ -0,0 +1,44 @@
+name: PHP CS Fixer
+
+on:
+  pull_request:
+
+permissions:
+  contents: write
+
+jobs:
+  cs-fixer:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          ref: ${{ github.head_ref }}
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Install PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.2'
+          tools: composer:v2.2
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Cache Composer packages
+        uses: actions/cache@v5
+        with:
+          path: vendor
+          key: ${{ runner.os }}-php-cs-fixer-${{ hashFiles('**/composer.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-php-cs-fixer-
+
+      - name: Install dependencies
+        run: composer install --prefer-dist
+
+      - name: Run PHP CS Fixer
+        run: ./bin/php-cs-fixer fix --diff
+
+      - name: Commit CS Fixer fixes
+        uses: stefanzweifel/git-auto-commit-action@v5
+        with:
+          commit_message: "style: apply php-cs-fixer changes"
+          commit_author: "github-actions[bot] <github-actions[bot]@users.noreply.github.com>"