Pass Linting CI/CD

[mehul0810]

I want to refactor code quality to ensure that it passes the linting CI/CD setup without changing existing functionality

[mehul0810]

Review reproduction notes from release/1.6.0:

• composer lint fails immediately because composer.json calls ./vendor/php-parallel-lint/php-parallel-lint/parallel-lint, but php-parallel-lint/php-parallel-lint is not in require-dev.
• composer test fails immediately because composer.json calls ./vendor/phpunit/phpunit/phpunit, but phpunit/phpunit is not in require-dev.
• composer phpstan reports 170 errors in the current checkout. The first blocker is config scope: phpstan.neon.dist uses paths: - . and does not exclude node_modules, so analysis enters node_modules/flatted/php/flatted.php. The excludePaths entry tests (?) also looks invalid and will not reliably exclude tests.
• npm run lint:js -- --format compact invoked eslint ... . and did not complete within 60s locally before I killed it. .eslintignore contains vendor and node_modules, but the script still needs a tighter target or verified ignore behavior so the CI/local lint path is bounded.

These are not new issues because this ticket already owns lint/static-analysis CI readiness, but they should be part of the acceptance criteria for closing it.

[mehul0810]

Release-readiness follow-up is covered by PR #99 against release/1.6.0. The PR is green across code style, frontend build, PHP lint, PHPUnit, PHPStan, and WordPress smoke checks. Leaving this open until #99 is merged so the milestone keeps the remaining release gate visible.

[mehul0810]

Completed on release/1.6.0 after PR #99 was merged.

Validation on the merge commit:

• CodeStyle: passed
• Lint: passed
• PHPUnit: passed
• Run PHPStan: passed
• Frontend: passed
• Playwright Smoke: passed

Local release-branch validation also passed composer validate, composer lint, composer test, composer phpstan, npm lint/build/package checks, and production zip inspection.