Summary

• Add client-side auth status tracking and route guards for protected dashboard pages
• Redirect unauthenticated users to the login page and preserve the intended destination
• Handle login/logout with axios so auth status is updated without relying on full-page form navigation

Test Plan

• pnpm exec eslint src/components/layout/MainNavbar/MainNavbar.vue src/layouts/Login.vue src/main.js src/router.js src/utils/auth.js
• pnpm build

Note: pnpm lint still fails on existing repository-wide lint issues outside this change.