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/features/accounts/application.py

@@ -28,11 +28,11 @@ class AccountApplicationMixin:
     def update_membership(self, payload: dict[str, Any]) -> None:
         self.accounts.update_membership(payload)
 
-    def register_account(self, username: str, password: str) -> dict[str, Any]:
-        return self.accounts.register(username, password)
+    def register_account(self, username: str, password: str, device_hash: str = "") -> dict[str, Any]:
+        return self.accounts.register(username, password, device_hash)
 
-    def login_account(self, username: str, password: str) -> dict[str, Any]:
-        return self.accounts.login(username, password)
+    def login_account(self, username: str, password: str, device_hash: str = "") -> dict[str, Any]:
+        return self.accounts.login(username, password, device_hash)
 
     def change_password(self, current_password: str, new_password: str) -> None:
         self.accounts.change_password(current_password, new_password)