Add automated E2E tests for frontend

[davidperezgar]

Summary

The plugin currently has no frontend or E2E test coverage. This issue tracks the implementation of automated End-to-End tests for the frontend using Playwright, covering the admin settings page and the key frontend JavaScript components.

Motivation

• 42 JavaScript files across 21 component directories with zero test coverage
• Interactive admin UI (toggles, settings) has no automated validation
• Frontend block enhancements (carousel, sticky column, animations, counter, etc.) are untested
• CI/CD pipeline only covers PHP linting/static analysis — no JS quality gates

Scope

Admin Settings Page

• Settings page renders correctly
• Feature toggles (Testimonials, Reading Progress, Back Button, Events CPT) can be enabled/disabled
• Settings are persisted after page reload

Frontend Components

• Carousel – navigation arrows work, auto-play works, responsive layout
• Sticky Column – element sticks during scroll, unsticks at correct position
• Reading Progress Bar – bar advances on scroll, reaches 100% at page bottom
• Counter – animates from 0 to target value when in viewport
• Headline Marquee – scrolls continuously, pauses on hover
• Animations – elements animate in when scrolled into view
• Back Button – navigates to previous page on click
• Accordion – opens/closes panels correctly

Implementation Plan

1. Install Playwright (@playwright/test) as a dev dependency
2. Add playwright.config.ts targeting a local WordPress test environment
3. Create test fixtures/helpers for WordPress login and page navigation
4. Write specs under tests/e2e/
5. Add test:e2e npm script
6. Add a GitHub Actions workflow (.github/workflows/e2e.yml) to run tests on PRs

Acceptance Criteria

• All listed test cases are implemented and passing
• Tests run in CI on every pull request targeting trunk
• Test results are available as GitHub Actions artifacts (HTML report)
• No existing build scripts are broken

Tech Stack

• Test runner: Playwright (@playwright/test)
• Language: TypeScript
• Environment: WordPress (local via wp-env or a Docker-based setup)
• Browsers: Chromium (primary), Firefox, WebKit (optional)