refactor(chat): remove unused upgrade state fields

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

@@ -38,8 +38,6 @@ function makeChatState(overrides: Partial<ChatState> = {}): ChatState {
     pendingReplyCount: 1,
     upgradePromptVisible: false,
     upgradeReason: null,
-    upgradeHint: null,
-    upgradeDetail: null,
     isLoadingMore: false,
     hasMore: true,
     historyOffset: 0,
@@ -169,12 +167,6 @@ describe("applyHttpSendOutput", () => {
     expect(nextState.isReplyingAI).toBe(false);
     expect(nextState.upgradePromptVisible).toBe(true);
     expect(nextState.upgradeReason).toBe("daily_limit");
-    expect(nextState.upgradeHint).toBeNull();
-    expect(nextState.upgradeDetail).toEqual({
-      type: "daily_msg_limit",
-      usedToday: 3,
-      limit: 3,
-    });
   });
 });
 

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

@@ -479,8 +479,6 @@ describe("chatMachine transitions", () => {
 
     expect(actor.getSnapshot().context.upgradePromptVisible).toBe(false);
     expect(actor.getSnapshot().context.upgradeReason).toBeNull();
-    expect(actor.getSnapshot().context.upgradeHint).toBeNull();
-    expect(actor.getSnapshot().context.upgradeDetail).toBeNull();
 
     actor.stop();
   });