MVP: Add landing + dashboard frontend, backend quiz/progress fixes, CI and tests

[BryanSeidy]

Motivation

• Deliver an MVP landing site and dashboard UI for the e‑learning product and wire it to existing course/quiz APIs.
• Improve backend API reliability by fixing model relations and authorization checks for quiz attempts and adding progress endpoints.
• Add CI, developer scripts and docs to make local builds/tests reproducible, including support for restricted networks via a composer mirror.

Description

• Frontend: added a landing site and dashboard (new pages, components, icons, SVGs, global styles), Next.js config tweaks, a smoke script and smoke.mjs checks, and new API client services for courses/quizzes/progress; updated package.json and added helper libs (cn, UI primitives).
• Backend: added markLessonCompleted and showCourseProgress to ProgressController, introduced helper resolvers in AttemptController and updated relation access, fixed model shapes (Question, Lesson, Quiz) and tightened auth/validation flows.
• Error handling & routing: centralized JSON API exception renderers in bootstrap/app.php for validation, authentication and generic server errors, and added request throttling to /api/auth endpoints in routes/api.php.
• Tooling & CI: added .github/workflows/ci.yml with frontend and backend jobs, a composer mirror install script backend/scripts/composer_install_with_mirror.sh, and a convenience script scripts/run_mvp_check.sh.
• Docs: updated README.md with run checklist, CI summary and architecture notes.
• Tests: updated several feature tests and added QuizProgressApiTest to cover quiz attempt submission and course progress endpoints.

Testing

• Ran frontend checks: npm run smoke, npm run lint, and npm run build as part of the CI job and local ./scripts/run_mvp_check.sh, and the smoke/lint/build steps completed successfully.
• Ran backend test suite via php artisan test which executed feature tests including AuthApiTest, CourseStructureApiTest, EnrollmentApiTest, and the new QuizProgressApiTest, and the test run completed successfully.
• Verified CI workflow configuration (.github/workflows/ci.yml) executes the above steps for push and pull_request events.

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Codex Task