# Change: Add Frontend Responsive Design and i18n Completion

## Why
The current frontend has usability issues on mobile and tablet devices - sidebar doesn't collapse properly, tables overflow, and some UI elements are not touch-friendly. Additionally, internationalization (i18n) is incomplete with some hardcoded Chinese text remaining in components.

## What Changes
- Implement responsive sidebar with collapsible behavior on small screens
- Add responsive table handling with horizontal scroll or card view
- Complete i18n translation coverage for all UI text
- Improve touch targets for mobile usability

## Impact
- Affected specs: dashboard
- Affected code:
  - `frontend/src/components/Layout.tsx` - Responsive sidebar
  - `frontend/src/components/*.tsx` - Responsive styles
  - `frontend/src/i18n/locales/*.json` - Translation files
  - `frontend/src/pages/*.tsx` - Replace hardcoded text