feat(frontend): add complete CSS design system and HTML shell
Create the Nexus Terminal design system with dark charcoal palette,
teal accent, and premium desktop application styling:
- tokens.css: Design tokens (colours, spacing, typography, layout)
- base.css: Modern reset, scrollbar, focus, and utility styles
- components.css: Buttons, forms, badges, dropdowns, notifications,
disclosure, search, empty state, tooltip, spinner
- layout.css: App grid shell (sidebar, tab bar, workspace, status bar)
- sidebar.css: Connection manager with sections, profile items, search
- tabs.css: Compact session tabs with status dots, protocol badges
- terminal.css: xterm.js container, RAW mode views, send bar, search
- forms.css: Profile editor sections, tag input, jump hosts, validation
- modals.css: Modal, drawer, confirmation, host key, settings dialogs
- index.html: Complete HTML shell with sidebar, tabs, workspace, status
andy
61e99e9fca