chore: initial project setup with backend, frontend, CI/CD, and documentation

Add complete NexaFabric project structure including:
- FastAPI backend with SQLAlchemy models, JWT auth, RBAC, audit logging, and provider interfaces
- React + TypeScript frontend with Vite, Tailwind CSS, TanStack Query, and Zustand
- Docker Compose configuration for PostgreSQL, Redis, API, worker, frontend, and nginx
- GitHub Actions and GitLab CI workflows for testing, linting, building, and security scanning
- Environment

backend/app/services/audit.py

@@ -0,0 +1,32 @@
+from sqlalchemy.orm import Session
+
+from app.models.domain import AuditLog
+
+
+def write_audit(
+    db: Session,
+    *,
+    action: str,
+    object_type: str,
+    object_id: str | None = None,
+    user_id: str | None = None,
+    old_values: dict | None = None,
+    new_values: dict | None = None,
+    result: str = "success",
+    error_text: str | None = None,
+) -> AuditLog:
+    audit = AuditLog(
+        action=action,
+        object_type=object_type,
+        object_id=object_id,
+        user_id=user_id,
+        old_values=old_values,
+        new_values=new_values,
+        result=result,
+        error_text=error_text,
+    )
+    db.add(audit)
+    db.commit()
+    db.refresh(audit)
+    return audit
+