Add Meme Sharing Analytics & Statistics

Track and display analytics for meme sharing activity (shares per platform, popular memes, trending topics) to provide insights to users.

## Current State
The app has sharing functionality but no tracking or analytics features.

## Tasks
- [ ] Create analytics tracking system in localStorage (client-side)
- [ ] Track: shares per platform, generated meme count, popular topics
- [ ] Create a new `/analytics` page to display user statistics
- [ ] Display charts using Chart.js or Recharts
- [ ] Add a statistics dashboard in the History page
- [ ] Export analytics as CSV/JSON

## Expected Output
- Users can see their meme generation statistics
- Visual charts showing sharing trends
- Popular topics and templates display
- Export functionality for data

## Files to Create/Modify
- `src/components/Analytics.jsx` (new)
- `src/components/History.jsx` (enhance)
- `src/utils/analyticsTracker.js` (new)
- `src/App.jsx` (add route)

## Dependencies
- `chart.js` or `recharts`
- `js-csv` for export

## Technical Details
- Use localStorage with timestamp-based analytics
- Implement data aggregation functions
- Create reusable chart components