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/services/ticket_service_test.go

@@ -81,7 +81,7 @@ func TestTicketServiceCreateTicketSetsPendingStatusAndTicketNo(t *testing.T) {
 	if len(progresses) != 1 {
 		t.Fatalf("expected initial progress, got %d", len(progresses))
 	}
-	if progresses[0].Content != "创建工单" || progresses[0].AuthorID != operator.UserID {
+	if progresses[0].Content != "Created ticket" || progresses[0].AuthorID != operator.UserID {
 		t.Fatalf("unexpected initial progress: %+v", progresses[0])
 	}