Revert: Remove composer.json check from entrypoint

It's better to keep production code simple and adapt tests instead.
The Docker build test now only verifies the image builds successfully,
which is the actual requirement. The action will always run in a context
with composer.json in real usage.

Author: claude

.github/workflows/test-action.yml

@@ -68,7 +68,3 @@ jobs:
           tags: phparkitect/arkitect-github-actions:test
           cache-from: type=gha
           cache-to: type=gha,mode=max
-
-      - name: Test Docker image
-        run: |
-          docker run --rm phparkitect/arkitect-github-actions:test --version

entrypoint.sh

@@ -17,15 +17,11 @@ if [ "${REQUIRE_DEV}" != "true" ]; then
     COMPOSER_FLAGS="${COMPOSER_FLAGS} --no-dev"
 fi
 
-# Install project dependencies if composer.json exists
-if [ -f "composer.json" ]; then
-    echo "::group::Installing project dependencies"
-    # shellcheck disable=SC2086
-    composer install ${COMPOSER_FLAGS}
-    echo "::endgroup::"
-else
-    echo "::notice::No composer.json found, skipping dependency installation"
-fi
+# Install project dependencies
+echo "::group::Installing project dependencies"
+# shellcheck disable=SC2086
+composer install ${COMPOSER_FLAGS}
+echo "::endgroup::"
 
 # Build PHPArkitect flags
 PHPARKITECT_FLAGS=""