feat: Redesign Artifacts page with GitLab-style UI

Complete redesign of the Artifacts page with better UX and error handling.

## Changes:

### 1. GitLab-Style Table Layout
- Professional table with expandable rows
- Job grouping with artifact file listings
- Status icons (success, failed, etc.)
- Cleaner visual hierarchy

### 2. Improved Error Handling
- Better error messages with notifications
- Show specific API error messages to user
- Loading states for download/delete actions
- Disabled states prevent duplicate actions

### 3. Enhanced Features
- Expandable rows to view artifact files
- File-by-file size display
- Commit information in expanded view
- "Open in GitLab" button for each job
- Responsive download/delete buttons

### 4. Better UX
- Clear visual feedback for actions
- Download progress indication
- Success/error toast notifications
- Confirmation dialogs for destructive actions

### 5. UI Improvements
- Collapsible file listings
- Status icons instead of badges
- Better spacing and typography
- Hover effects on rows
- File count indicators

## Example Features:
- Click chevron to expand and see artifact files
- Download button with loading state
- Error messages show actual API errors
- Clean GitLab-inspired design

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: ismoilovdevml