施工(HEL-226): 实现登录门户与本机免密切换账号

用设备 Cookie 和授权表记住本机已验证账号，登录页按确认样图做成门户，不再把密码写进浏览器。

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: multica-agent <github@multica.ai>

backend/http/dispatch.py

@@ -7,6 +7,8 @@ from urllib.parse import urlparse
 PUBLIC_POST_HANDLERS = {
     "/api/auth/register": "auth_register",
     "/api/auth/login": "auth_login",
+    "/api/auth/switch": "auth_switch",
+    "/api/auth/forget": "auth_forget",
 }
 
 AUTHENTICATED_POST_HANDLERS = {