fix: optimize console statistics queries to prevent freezing and improve

[Ember-Moth]

• Replace N+1 daily loop in QueryServerTotalData with batch IN query
• Parallelize 3 traffic_log scans using sync.WaitGroup
• Replace per-server FindOneServer N+1 calls with batch WHERE id IN query
• Add Redis caching (60s TTL) for all three console statistics endpoints
• Fix date boundary handling: use >= start AND < nextDay instead of BETWEEN
• Add migration 02126: composite index on system_logs(type, date)