refactor(chat): reorganize helper functions and update imports

src/stores/chat/__tests__/chat-helpers.test.ts

@@ -7,7 +7,7 @@ import {
   countLockedHistoryMessages,
   localMessagesToUi,
   sendResponseToUiMessage,
-} from "@/stores/chat/chat-machine.helpers";
+} from "@/stores/chat/helper";
 
 function makeResponse(
   overrides: Partial<Parameters<typeof ChatSendResponse.from>[0]> = {},

src/stores/chat/__tests__/chat-machine.test-utils.ts

@@ -10,7 +10,7 @@ import type { ChatEvent } from "@/stores/chat/chat-events";
 import type {
   UnlockMessageOutput as MachineUnlockMessageOutput,
   UnlockMessageRequest,
-} from "@/stores/chat/chat-machine.helpers";
+} from "@/stores/chat/helper/unlock";
 
 export interface SendMessageHttpOutput {
   response: ChatSendResponse;

src/stores/chat/__tests__/chat-promotion.test.ts

@@ -6,7 +6,7 @@ import {
   appendPromotionMessage,
   applyPromotionUnlockOutput,
   createChatPromotionState,
-} from "@/stores/chat/chat-promotion";
+} from "@/stores/chat/helper/promotion";
 
 const promotion: PendingChatPromotion = {
   promotionType: "image",