refactor(chat): extract XState actors into chat-machine.actors.ts

- Split chat state machine actors (chatInit, sendMessageHttp, loadMoreHistory, chatWebSocket) into a dedicated module
- Add comprehensive console logging across the chat state machine for full trace debugging
- Comment out margin on text bubble CSS for layout adjustment
- Add debug logging to chat input bar send handler
- Clean up redundant comments in auth-screen component

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

@@ -0,0 +1,116 @@
+/**
+ * Chat 状态机：纯函数 + 数据加载
+ *
+ * 从 `chat-machine.ts` 抽出的"helpers"段：
+ *   - 翻页大小常量
+ *   - 仓库注入（接口类型 → 单例）
+ *   - DTO ↔ UiMessage 映射（**纯函数** —— 可单测）
+ *   - Result → number 映射（**纯函数** —— 可单测）
+ *   - 初始数据装配（**仅**游客有意义 —— `chatInitActor` 调用）
+ *
+ * 设计目标：
+ *   - helpers **无 XState 依赖**（可独立 import / 测试）
+ *   - actors 依赖 helpers（import）
+ *   - machine 依赖 actors（import）—— **不**直接依赖 helpers
+ */
+
+import type { UiMessage } from "@/models/chat/ui-message";
+import { chatRepository } from "@/data/repositories/chat_repository";
+import type { IChatRepository } from "@/data/repositories/interfaces";
+import { ChatStorage } from "@/data/storage/chat/chat_storage";
+import { AuthStorage } from "@/data/storage/auth/auth_storage";
+import { Result } from "@/utils/result";
+
+// ============================================================// Constants
+// ============================================================
+/** 翻历史每页大小（**仅** `loadMoreHistoryActor` 用） */
+export const PAGE_SIZE = 20;
+
+// ============================================================// Repository injection
+// ============================================================
+// 仓库以接口类型注入：调用面只看接口，运行时仍是同一单例
+export const chatRepo: IChatRepository = chatRepository;
+
+// ============================================================// DTO ↔ UiMessage 映射
+// ============================================================
+/**
+ * ChatMessage[] → UiMessage[]（**纯函数**）
+ * - 与 Dart `LocalMessage → ChatMessage` 等价
+ * - 业务事实：`role === "assistant"` → `isFromAI: true`
+ */
+export function localMessagesToUi(
+  records: ReadonlyArray<{
+    content: string;
+    role: string;
+    createdAt: string;
+  }>,
+): UiMessage[] {
+  return records.map((m) => ({
+    content: m.content,
+    isFromAI: m.role === "assistant",
+    date: m.createdAt,
+  }));
+}
+
+// ============================================================// Result → number 映射
+// ============================================================
+/** 日配额 Result → number（**纯函数**） */
+export function mapQuotaResult(
+  r: Result<{ remaining: number } | null>,
+  fallback: number,
+): number {
+  if (r.success && r.data != null) return r.data.remaining;
+  return fallback;
+}
+
+/** 总配额 Result → number（**纯函数**） */
+export function mapTotalQuotaResult(
+  r: Result<number | null>,
+  fallback: number,
+): number {
+  if (r.success && r.data != null) return r.data;
+  return fallback;
+}
+
+// ============================================================// Initial data
+// ============================================================
+export interface InitResult {
+  localMessages: UiMessage[];
+  isGuest: boolean;
+  guestRemainingQuota: number;
+  guestTotalQuota: number;
+}
+
+/**
+ * 读取初始数据（`chatInitActor` 调用）
+ *
+ * - `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。
+ * - 配额 fallback 0 —— 非游客路径用不到；onDone 会**条件**赋。
+ */
+export async function readInitData(): Promise<InitResult> {
+  const chatStorage = ChatStorage.getInstance();
+  const isGuest = !AuthStorage.getInstance().hasLoginToken();
+
+  const [dailyResult, totalResult, localResult] = await Promise.all([
+    chatStorage.getGuestDailyChatQuota(),
+    chatStorage.getGuestTotalQuota(),
+    isGuest ? chatRepo.getLocalMessages() : Promise.resolve(null),
+  ]);
+
+  return {
+    isGuest,
+    guestRemainingQuota: mapQuotaResult(
+      dailyResult as Result<{ remaining: number } | null>,
+      0,
+    ),
+    guestTotalQuota: mapTotalQuotaResult(
+      totalResult as Result<number | null>,
+      0,
+    ),
+    localMessages:
+      localResult && Result.isOk(localResult) && localResult.data
+        ? localMessagesToUi(localResult.data)
+        : [],
+  };
+}