feat(gateways): Introduce gateway model and update agent provisioning templates

backend/app/models/gateways.py

@@ -0,0 +1,20 @@
+from __future__ import annotations
+
+from datetime import datetime
+from uuid import UUID, uuid4
+
+from sqlmodel import Field, SQLModel
+
+
+class Gateway(SQLModel, table=True):
+    __tablename__ = "gateways"
+
+    id: UUID = Field(default_factory=uuid4, primary_key=True)
+    name: str
+    url: str
+    token: str | None = Field(default=None)
+    main_session_key: str
+    workspace_root: str
+    skyll_enabled: bool = Field(default=False)
+    created_at: datetime = Field(default_factory=datetime.utcnow)
+    updated_at: datetime = Field(default_factory=datetime.utcnow)