fix: 🎨 AI Chat assistant with neo-brutalism styling + dark mode vars

fix: 🎨 Notifications dropdown using CSS vars for proper dark mode

feat: Application reminders, timeline API, global search, AI chat assistant, Cmd+K command palette, job comparison page, saved jobs with folders

feat: Add CI/CD (GitHub Actions), E2E tests (Playwright), deploy scripts (Fly.io + Vercel), admin dashboard, notifications dropdown, Postman collection