ems-core v1.0.0: Standard EMS platform core

Shared backend + frontend for multi-customer EMS deployments.
- 12 enterprise modules: quota, cost, charging, maintenance, analysis, etc.
- 120+ API endpoints, 37 database tables
- Customer config mechanism (CUSTOMER env var + YAML config)
- Collectors: Modbus TCP, MQTT, HTTP API, Sungrow iSolarCloud
- Frontend: React 19 + Ant Design + ECharts + Three.js
- Infrastructure: Redis cache, rate limiting, aggregation engine

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/models/setting.py

@@ -0,0 +1,13 @@
+from sqlalchemy import Column, Integer, String, Text, DateTime
+from sqlalchemy.sql import func
+from app.core.database import Base
+
+
+class SystemSetting(Base):
+    __tablename__ = "system_settings"
+
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    key = Column(String(100), unique=True, nullable=False, index=True)
+    value = Column(Text, nullable=False, default="")
+    description = Column(String(255))
+    updated_at = Column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())