fix(app-iced, presenter): M114 r3 —— 登录成功提示走 i18n key+参数，离线名字提交判据与 host 同源

- 新增 Key::AccountLoginSucceeded（Signed in as {name} / 已登录 {name}）：
  presenter 不再拼「已登录：{name}」这类人类可读句子（复审 r1 P1-1 的收尾）
- valid_offline_name 从 host 搬到 dto（UI 与 host 共用的同一个判据），
  Form::offline_ready 改用它：按钮不再「亮着但必然失败」
- 视图模型测试：成功提示按 i18n 渲染进 on_screen；离线提交判据加「太短也拒绝」断言

crates/presenter/src/dto/mod.rs

@@ -29,9 +29,9 @@ mod settings;
 mod versions;
 
 pub use accounts::{
-    looks_like_jwt, redact, AccountKind, AccountNotice, AccountNoticeCode, AccountView,
-    AuthlibLoginView, AuthlibRequest, DeviceLoginPhase, DeviceLoginView, LoginFailure, SkinImage,
-    REDACTED,
+    looks_like_jwt, redact, valid_offline_name, AccountKind, AccountNotice, AccountNoticeCode,
+    AccountView, AuthlibLoginView, AuthlibRequest, DeviceLoginPhase, DeviceLoginView, LoginFailure,
+    SkinImage, REDACTED,
 };
 pub use agent::{AgentEvent, ChatMessage, ChatRole, ConfirmRequest, Sensitivity, ToolCallView};
 pub use content::{