MVP: add frontend product pages, CI, backend API improvements, and tests

[BryanSeidy]

Motivation

• Provide a minimal end-to-end MVP with landing/dashboard/course/lesson/quiz flows, automated checks and CI to validate the whole stack.
• Harden API error handling and make backend/frontend integration predictable for smoke tests and automated tests.

Description

• Add GitHub Actions CI at .github/workflows/ci.yml to run frontend smoke/lint/build and backend composer install, migrations and php artisan test in CI.
• Implement frontend MVP pages, components and styles (landing, dashboard, courses, course detail, lesson page, quiz page, exercises, exams, planning, profile, AppNav, and global CSS), add npm smoke check (frontend/scripts/smoke.mjs) and update frontend/package.json with smoke script.
• Add frontend API service clients courseService, quizService, and progressService, and helpers scripts/run_mvp_check.sh and backend/scripts/composer_install_with_mirror.sh for reproducible local runs and restricted-network installs.
• Backend changes include improved exception rendering in backend/bootstrap/app.php for ValidationException, AuthenticationException and generic errors, route throttling added to auth endpoints in backend/routes/api.php, progress and quiz/attempt controller refactors to resolve relations correctly, and model fixes for Question, Lesson, and Quiz to align attribute and relation names.
• Update and add automated tests in backend/tests/Feature: refactor AuthApiTest, CourseStructureApiTest, EnrollmentApiTest, and add QuizProgressApiTest to cover quiz attempt flow and course progress.

Testing

• Ran the frontend checks npm run smoke, npm run lint, and npm run build and they completed successfully.
• Ran backend test suite with php artisan test, which executed the modified and new feature tests including AuthApiTest, CourseStructureApiTest, EnrollmentApiTest, and QuizProgressApiTest, and all tests passed.
• Executed the combined local verification script ./scripts/run_mvp_check.sh to validate install, build, migrations and tests end-to-end, and it completed without errors.

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Codex Task