refactor(chat): decouple chat state from auth and gate quota alerts to guests

- Remove ChatAuthStatusChanged dispatch from auth login flow; chat screen now subscribes directly to auth state machine (loginStatus) to derive isGuest and drive WS lifecycle
- Gate quota-exceeded and warning dialogs to guests only (non-guests have no message limit)
- Dispatch ChatLoadMoreHistory for non-guest initial load vs ChatInit for guests
- Fix AppConstants import path from @/core/constants/app_constants to @/core/app_constants
- Add defensive isGuest checks in quota effects to prevent non-guest quota triggers

src/stores/chat/chat-machine.ts

@@ -13,6 +13,16 @@
  *   - HTTP 操作用 `fromPromise` actor（一次性 Promise）
  *   - 保持事件类型名与原 Dart 一致，便于业务层迁移对照
  *   - actions 全部 inline 在 setup() 中（确保类型推断正确）
+ *
+ * **鉴权解耦**：
+ *   chat 机器**不**感知鉴权状态 —— `isGuest` 字段已删（由 chat-screen 派生自 auth.loginStatus）。
+ *   WebSocket 管理也由 chat-screen 监听 auth 状态机后驱动。
+ *
+ * **配额（**仅**游客）**：
+ *   - `guestRemainingQuota` / `guestTotalQuota` **仅**游客有意义
+ *   - 非游客"无消息限制"（业务事实）—— 永不被赋值
+ *   - chat-screen 派 `ChatInit` 时（**只**在 guest）→ onDone 条件赋
+ *   - `appendUserMessage` 减 `Math.max(0, q - 1)` —— 非游客 0-1=0 天然 no-op
  */
 import { setup, fromPromise, assign } from "xstate";
 
@@ -85,6 +95,8 @@ interface InitResult {
 
 async function readInitData(): Promise<InitResult> {
   const chatStorage = ChatStorage.getInstance();
+  // isGuest 在 chat 业务层仅用于"是否加载本地历史" + "onDone 条件赋配额" —— **不**是鉴权信号
+  // 鉴权判断已上提到 chat-screen 派生
   const isGuest = !AuthStorage.getInstance().hasLoginToken();
 
   const [dailyResult, totalResult, localResult] = await Promise.all([
@@ -95,13 +107,14 @@ async function readInitData(): Promise<InitResult> {
 
   return {
     isGuest,
+    // fallback 0 —— 非游客路径用不到；onDone 会**条件**赋
     guestRemainingQuota: mapQuotaResult(
       dailyResult as Result<{ remaining: number } | null>,
-      40,
+      0,
     ),
     guestTotalQuota: mapTotalQuotaResult(
       totalResult as Result<number | null>,
-      50,
+      0,
     ),
     localMessages:
       localResult && Result.isOk(localResult) && localResult.data
@@ -145,8 +158,7 @@ const loadMoreHistoryActor = fromPromise<
   };
 });
 
-// ============================================================
-// Machine
+// ============================================================// Machine
 // ============================================================
 export const chatMachine = setup({
   types: {
@@ -171,6 +183,8 @@ export const chatMachine = setup({
           },
         ],
         isReplyingAI: true,
+        // 游客减配额；非游客 0 - 1 = max(0, -1) = 0 —— **天然 no-op**（业务事实"非游客无限制"）
+        guestRemainingQuota: Math.max(0, context.guestRemainingQuota - 1),
       };
     }),
 
@@ -187,6 +201,8 @@ export const chatMachine = setup({
           },
         ],
         isReplyingAI: true,
+        // 游客减配额；非游客 no-op
+        guestRemainingQuota: Math.max(0, context.guestRemainingQuota - 1),
       };
     }),
 
@@ -223,10 +239,6 @@ export const chatMachine = setup({
       return { messages, isReplyingAI: false };
     }),
 
-    refreshAuthStatus: assign(() => ({
-      isGuest: !AuthStorage.getInstance().hasLoginToken(),
-    })),
-
     incrementQuotaExceeded: assign(({ context }) => ({
       quotaExceededTrigger: context.quotaExceededTrigger + 1,
     })),
@@ -248,9 +260,6 @@ export const chatMachine = setup({
         ChatSendImage: {
           actions: "appendUserImage",
         },
-        ChatAuthStatusChanged: {
-          actions: "refreshAuthStatus",
-        },
         ChatAISentenceReceived: {
           actions: "appendOrUpdateAISentence",
         },
@@ -269,11 +278,18 @@ export const chatMachine = setup({
         src: "chatInit",
         onDone: {
           target: "ready",
-          actions: assign({
-            messages: ({ event }) => event.output.localMessages,
-            isGuest: ({ event }) => event.output.isGuest,
-            guestRemainingQuota: ({ event }) => event.output.guestRemainingQuota,
-            guestTotalQuota: ({ event }) => event.output.guestTotalQuota,
+          // **条件赋**：仅 isGuest 时初始化配额（业务事实"非游客无消息限制"）
+          //   - 游客：messages + quota 都更新
+          //   - 非游客：仅 messages（local 空），quota 保持 default 0（不更新其值）
+          actions: assign(({ event }) => {
+            const updates: Partial<ChatState> = {
+              messages: event.output.localMessages,
+            };
+            if (event.output.isGuest) {
+              updates.guestRemainingQuota = event.output.guestRemainingQuota;
+              updates.guestTotalQuota = event.output.guestTotalQuota;
+            }
+            return updates;
           }),
         },
         onError: {
@@ -293,9 +309,6 @@ export const chatMachine = setup({
         },
         ChatLoadMoreHistory: "loadingMoreHistory",
         ChatScreenInvisible: "idle",
-        ChatAuthStatusChanged: {
-          actions: "refreshAuthStatus",
-        },
         ChatAISentenceReceived: {
           actions: "appendOrUpdateAISentence",
         },