feat(chat): load model options from backend

src/lib/chatStream.ts

@@ -1,9 +1,7 @@
 import { apiFetch } from "@/lib/apiFetch";
 import { config } from "@config/config";
 
-export type AgentModel =
-  | "deepseek/deepseek-v4-flash"
-  | "deepseek/deepseek-v4-pro";
+export type AgentModel = string;
 
 export type PermissionReply = "once" | "always" | "reject";
 export type AgentApprovalMode = "request" | "always";