.commit_msg

feat(ui): implement responsive mobile layout and glassmorphic sidebar

This commit completely revamps the mobile user experience by introducing a responsive grid system and a new glassmorphic mobile navigation sidebar. The previous layout broke on small viewports due to fixed widths and inline flex containers without wrap.

Key changes:
- **Mobile Navigation Menu**: Added a new `MobileSidebar` component that overlays the screen on mobile devices with a blur backdrop (`backdrop-filter: blur(20px)`), containing quick actions (History, API Keys, Theme Toggle, Auth) without shifting page content.
- **Responsive Layout System**: Migrated hardcoded inline styles in `App.tsx` and sub-components to robust CSS classes in `index.css` under a `max-width: 768px` media query.
- **Adaptive Components**:
  - `InputSection`: Stacks the search input and submit button vertically on mobile.
  - `SummarySection`: Wraps the stat cards, sub-scores, and time distribution charts into mobile-friendly columns.
  - `HistorySidebar`: Updated fixed 400px width to `min(400px, 100vw)` to prevent overflow on smaller screens like the iPhone SE.
- **Refactoring**: Cleaned up the header controls in `App.tsx` to conditionally render the new hamburger toggle button exclusively for mobile viewports.

This establishes a solid foundation for future mobile capabilities (e.g., Progressive Web App).