fix: 修复 USER_TYPE=ant 时 TUI 无法启动的问题

反编译版本中 global.d.ts 声明的全局函数运行时未定义，
通过显式 import、stub 组件和全局 polyfill 修复。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/utils/context.ts

@@ -3,6 +3,7 @@ import { CONTEXT_1M_BETA_HEADER } from '../constants/betas.js'
 import { getGlobalConfig } from './config.js'
 import { isEnvTruthy } from './envUtils.js'
 import { getCanonicalName } from './model/model.js'
+import { resolveAntModel } from './model/antModels.js'
 import { getModelCapability } from './model/modelCapabilities.js'
 
 // Model context window size (200k tokens for all models right now)