Fix php-cs-fixer Docker build for older PHP versions

Extract php-cs-fixer versions from composer.json and install only the
required packages instead of all dev dependencies. This avoids
dependency resolution failures when transitive dependencies drop support
for older PHP versions like 8.0.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: spawnia

.php-cs-fixer.dockerfile

@@ -9,8 +9,13 @@ RUN apt-get update \
 
 COPY --from=composer:2.9 /usr/bin/composer /usr/bin/composer
 
-COPY composer.json /deps/
-RUN composer update --working-dir=/deps --no-interaction --quiet
+COPY composer.json /tmp/
+RUN VERSION=$(grep -oP '"friendsofphp/php-cs-fixer":\s*"\K[^"]+' /tmp/composer.json) \
+  && MLL_VERSION=$(grep -oP '"mll-lab/php-cs-fixer-config":\s*"\K[^"]+' /tmp/composer.json) \
+  && mkdir /deps \
+  && composer require --working-dir=/deps --no-interaction --quiet \
+    "friendsofphp/php-cs-fixer:$VERSION" \
+    "mll-lab/php-cs-fixer-config:$MLL_VERSION"
 ENTRYPOINT ["/deps/vendor/bin/php-cs-fixer", "fix", "--config=/app/.php-cs-fixer.php"]
 
 WORKDIR /app