- Add buyEnabled field to TradingConfig in trading-service with migration
- Add API endpoints for get/set buy enabled status in admin controller
- Add buy function switch card in mining-admin-web trading page
- Implement buyEnabledProvider in mining-app with 2-minute cache
- Show "待开启" when buy function is disabled in trading page
- Add real-time asset value refresh in asset page (1-second updates)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>