feat: initialize monorepo with full dev team best practices

- Unified monorepo with backend (Express), frontend (Next.js), and devops
- Backend: ESLint, Prettier, Jest tests (3 passing), health endpoint, .env.example
- Frontend: Fixed build errors, fixed all lint errors (0 remaining), tests passing
- DevOps: Docker Compose with PostgreSQL, backend, frontend + healthchecks
- CI/CD: 3 GitHub Actions workflows (backend, frontend, docker integration)
- DX: Husky pre-commit hooks with smart change detection
- Docs: Root README with architecture, CONTRIBUTING.md, PR template

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.env.example

@@ -0,0 +1,20 @@
+# ============================================
+# Website Monitoring — Environment Variables
+# ============================================
+# Copy this file to .env and fill in your values.
+# Used by docker-compose and local development.
+
+# ── PostgreSQL ──────────────────────────────
+POSTGRES_USER=monitoring
+POSTGRES_PASSWORD=monitoring_pass
+POSTGRES_DB=monitoring
+
+# ── Backend ─────────────────────────────────
+PORT=5000
+DATABASE_URL=postgresql://monitoring:monitoring_pass@localhost:5432/monitoring
+CORS_ORIGIN=http://localhost:3000
+
+# ── Frontend (Supabase) ────────────────────
+NEXT_PUBLIC_SUPABASE_URL=https://your-project.supabase.co
+NEXT_PUBLIC_SUPABASE_ANON_KEY=your-anon-key
+SUPABASE_SERVICE_ROLE_KEY=your-service-role-key