add initial implementation of auth gateway with models, routes, and session management

containers/auth-gateway/auth_gateway/models/routes.py

@@ -0,0 +1,16 @@
+from pydantic import BaseModel, Field
+
+
+class RoutePolicyBindingModel(BaseModel):
+    id: str | None = None
+    path_prefix: str
+    policy: str
+
+
+class AppRoutesModel(BaseModel):
+    routes: list[RoutePolicyBindingModel] = Field(default_factory=list)
+    default_policy: str | None = None
+
+
+class RoutesFileModel(BaseModel):
+    entries: dict[str, AppRoutesModel] = Field(default_factory=dict)