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/services/audit.py

@@ -0,0 +1,32 @@
+from sqlalchemy.ext.asyncio import AsyncSession
+from app.models.user import AuditLog
+
+
+async def log_audit(
+    db: AsyncSession,
+    user_id: int | None,
+    action: str,
+    resource: str,
+    detail: str = "",
+    ip_address: str | None = None,
+):
+    """Write an audit log entry.
+
+    Args:
+        db: async database session (must be flushed/committed by caller)
+        user_id: ID of the acting user (None for system actions)
+        action: one of login, create, update, delete, export, view,
+                acknowledge, resolve
+        resource: one of user, device, alarm, report, system, auth
+        detail: human-readable description
+        ip_address: client IP if available
+    """
+    entry = AuditLog(
+        user_id=user_id,
+        action=action,
+        resource=resource,
+        detail=detail,
+        ip_address=ip_address,
+    )
+    db.add(entry)
+    # Don't flush here — let the caller's transaction handle it