Fix code quality issues

- Fix phpstan.neon file structure
- Fix Markdown formatting in docs/code-quality-setup.md
- Add proper language specifier to .env code block in README.md
- Add blank lines around code blocks in README.md
- Add newline at end of GitHub workflow file

.github/workflows/code-quality.yml

@@ -149,4 +149,4 @@ jobs:
         uses: github/codeql-action/upload-sarif@v3
         with:
           sarif_file: results.sarif
-        continue-on-error: true
+        continue-on-error: true