feat: improve get_top_downloaded_packages with robust fallback system

- Add curated popular packages database with 100+ packages
- Implement GitHub API integration for real-time popularity metrics
- Create multi-tier fallback strategy (live API -> curated -> enhanced)
- Add period scaling and realistic download estimates
- Provide rich metadata with categories and descriptions

test_improved.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python3
+"""Test script for the improved get_top_packages_by_downloads function."""
+
+import asyncio
+from pypi_query_mcp.tools.download_stats import get_top_packages_by_downloads
+
+async def test_improved():
+    try:
+        result = await get_top_packages_by_downloads('month', 10)
+        print('✅ Success! Result keys:', list(result.keys()))
+        print(f'Number of packages returned: {len(result.get("top_packages", []))}')
+        print(f'Data source: {result.get("data_source")}')
+        print(f'Methodology: {result.get("methodology")}')
+        
+        print('\nTop 5 packages:')
+        for i, pkg in enumerate(result.get('top_packages', [])[:5]):
+            downloads = pkg.get('downloads', 0)
+            stars = pkg.get('github_stars', 'N/A')
+            estimated = '(estimated)' if pkg.get('estimated', False) else '(real)'
+            github_enhanced = ' 🌟' if pkg.get('github_enhanced', False) else ''
+            print(f'{i+1}. {pkg.get("package", "N/A")} - {downloads:,} downloads {estimated}{github_enhanced}')
+            if stars != 'N/A':
+                print(f'   GitHub: {stars:,} stars, {pkg.get("category", "N/A")} category')
+                
+        # Test different periods
+        print('\n--- Testing different periods ---')
+        for period in ['day', 'week', 'month']:
+            result = await get_top_packages_by_downloads(period, 3)
+            top_3 = result.get('top_packages', [])
+            print(f'{period}: {len(top_3)} packages, avg downloads: {sum(p.get("downloads", 0) for p in top_3) // max(len(top_3), 1):,}')
+            
+        print('\n--- Testing different limits ---')
+        for limit in [5, 20, 50]:
+            result = await get_top_packages_by_downloads('month', limit)
+            packages = result.get('top_packages', [])
+            real_count = len([p for p in packages if not p.get('estimated', False)])
+            print(f'Limit {limit}: {len(packages)} packages returned, {real_count} with real stats')
+                
+    except Exception as e:
+        print(f'❌ Error: {e}')
+        import traceback
+        traceback.print_exc()
+
+if __name__ == '__main__':
+    asyncio.run(test_improved())