refactor: remove LocaleSwitcher component and update locale handling

- Removed LocaleSwitcher from NavUser, SiteHeader, and WorkbenchHeader components.
- Updated tests to reflect the removal of LocaleSwitcher.
- Changed default locale from "en-US" to "zh-CN" in i18n configuration.
- Refactored locale resolution logic to read configured locale without relying on browser language detection.
- Updated AgentDesk SDK to support language configuration from public API.
- Cleaned up unused auth options fetching in the auth API.

internal/bootstrap/init.go

@@ -4,6 +4,7 @@ import (
 	"agent-desk/internal/ai/rag/vectordb"
 	"agent-desk/internal/oidcclient"
 	"agent-desk/internal/pkg/config"
+	"agent-desk/internal/pkg/i18nx"
 	"agent-desk/internal/pkg/logx"
 	"agent-desk/internal/services/cronx"
 	"agent-desk/internal/wxwork"
@@ -20,6 +21,7 @@ func Init(configPath string) error {
 		return err
 	}
 	config.SetCurrent(cfg)
+	i18nx.SetDefaultLocale(cfg.LanguageOrDefault())
 
 	logx.Init(logx.Config{
 		Level:     cfg.Logger.Level,