Fix UI components (Badge, Button, Card, Input, ProgressBar, ScoreBar,
ChatPanel) to use CSS variables instead of old theme object pattern.
Clean up barrel exports (common/index.ts, layout/index.ts) and remove
stale router/tabs import from shell-config.ts. Build: tsc zero errors,
Vite production build succeeds (1760 modules, 270 kB JS, 22 kB CSS).
- Added HeaderLayout component for the application header.
- Introduced KeepAliveViewport for managing tab states and rendering.
- Created TabNav for tab navigation with animated indicator.
- Removed old Tabs component in favor of new layout structure.
- Updated routing with AppRouter and defined appTabs for navigation.
- Enhanced theme context to manage dark mode styles.
- Added new UI components: Badge, Button, Separator, and Tabs.
- Refactored pages to utilize new layout components and improve responsiveness.
- Updated global styles for better theming and layout consistency.
- Introduced TypeScript path aliases for cleaner imports.
feat(agent): update import for agent session service
feat(openai): add context truncation check in OpenAI answer generator
docs(README): update frontend environment file conventions
fix(vite): default local frontend development to local backend
