feat(login): switch login to google oauth flow

- add typed OauthTokenRequest interface for oauth token API
- remove unused AgreePopup component and all agreement-related logic
- rewrite login page to implement full Google OAuth2 login flow including state generation, callback validation and redirect handling

src/api/login.ts

@@ -1,7 +1,15 @@
 import { request } from "../utils/request";
 
 // 获取oauth token
-export function oauthToken(args: any) {
+export interface OauthTokenRequest {
+  clientId: string;
+  grant_type?: string;
+  openIdCode?: string[];
+  scope?: string;
+  [property: string]: any;
+}
+
+export function oauthToken(args: OauthTokenRequest) {
   return request({
     url: "/auth/oauth2/token",
     method: "post",