Refactor localization strings to English across various services and UI components

- Updated titles and subtitles in channel_service.go for web channel and WeChat MP channel configurations.
- Changed handoff messages in conversation_human_dispatch_service.go to English.
- Modified notification messages in event handlers for ticket and conversation assignments to English.
- Adjusted ticket creation messages in ticket_service.go to reflect English localization.
- Updated default locale settings in i18n configuration files to English (en-US).
- Changed HTML language attribute in layout.tsx to English.
- Refactored widget locale detection logic in agent-desk-sdk.ts to prioritize English.

internal/pkg/i18nx/context.go

@@ -6,15 +6,15 @@ const contextLocaleKey = "i18nx.locale"
 
 func Locale(ctx *gin.Context) string {
 	if ctx == nil {
-		return LocaleZhCN
+		return DefaultLocale
 	}
 	value, ok := ctx.Get(contextLocaleKey)
 	if !ok {
-		return LocaleZhCN
+		return DefaultLocale
 	}
 	locale, ok := value.(string)
 	if !ok {
-		return LocaleZhCN
+		return DefaultLocale
 	}
 	return NormalizeLocale(locale)
 }