Add unique IP count and duplicate detection to sites page

The sites page previously showed total IP count which included duplicates
across multiple sites, leading to inflated numbers. Now displays unique
IP count as the primary metric with duplicate count shown when present.

- Add get_global_ip_stats() method to SiteService for unique/duplicate counts
- Update /api/sites?all=true endpoint to include IP statistics
- Update sites.html to display unique IPs with optional duplicate indicator
- Update API documentation with new response fields

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

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

app/web/api/sites.py

@@ -36,9 +36,15 @@ def list_sites():
         if request.args.get('all', '').lower() == 'true':
             site_service = SiteService(current_app.db_session)
             sites = site_service.list_all_sites()
+            ip_stats = site_service.get_global_ip_stats()
 
             logger.info(f"Listed all sites (count={len(sites)})")
-            return jsonify({'sites': sites})
+            return jsonify({
+                'sites': sites,
+                'total_ips': ip_stats['total_ips'],
+                'unique_ips': ip_stats['unique_ips'],
+                'duplicate_ips': ip_stats['duplicate_ips']
+            })
 
         # Get and validate query parameters
         page = request.args.get('page', 1, type=int)